[Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A] Ticklefish:
Here's your code:

<?xml version="1.0" encoding="utf-8"?>
<com.android.systemui.statusbar.phone.PhoneStatusBarView android:background="@drawable/status_bar_custom_background" android:focusable="true" android:descendantFocusability="afterDescendants" android:layout_width="fill_parent" android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui">
<LinearLayout android:orientation="horizontal" android:id="@id/icons" android:paddingLeft="6.0dip" android:paddingRight="6.0dip" android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout android:orientation="horizontal" android:layout_width="0.0dip" android:layout_height="fill_parent" android:layout_weight="1.0">
<com.android.systemui.statusbar.phone.CarrierLabel android:textAppearance="@android:style/TextAppearance.StatusBar.Icon" android:textColor="@android:color/transparent" android:gravity="center_vertical" android:orientation="horizontal" android:background="@drawable/carrier_logo" android:layout_width="wrap_content" android:layout_height="wrap_content" android:singleLine="true" android:layout_alignParentLeft="true" />
<com.android.systemui.statusbar.policy.Traffic android:textAppearance="@style/TextAppearance.StatusBar.Battery" android:gravity="left|center" android:id="@id/data_speed_meter" android:paddingRight="3.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="true" />
<com.android.systemui.statusbar.StatusBarIconView android:id="@id/moreIcon" android:visibility="gone" android:layout_width="@dimen/status_bar_icon_size" android:layout_height="fill_parent" android:src="@drawable/stat_notify_more" />
<com.android.systemui.statusbar.StatusBarIconView android:id="@id/moreIcon" android:visibility="gone" android:layout_width="@dimen/status_bar_icon_size" android:layout_height="fill_parent" android:src="@drawable/stat_notify_more" />
<com.android.systemui.statusbar.phone.IconMerger android:gravity="center_vertical" android:orientation="horizontal" android:id="@id/notificationIcons" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_alignParentLeft="true" />
</LinearLayout>
<LinearLayout android:gravity="center_vertical" android:orientation="horizontal" android:id="@id/statusIcons" android:layout_width="wrap_content" android:layout_height="fill_parent" />
<LinearLayout android:gravity="center" android:orientation="horizontal" android:id="@id/signal_battery_cluster" android:paddingLeft="2.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent">
<include android:id="@id/signal_cluster" android:layout_width="wrap_content" android:layout_height="wrap_content" layout="@layout/signal_cluster_view" />
<include android:id="@id/signal_cluster_text" android:layout_width="wrap_content" android:layout_height="wrap_content" layout="@layout/signal_cluster_text_view" />
<include android:id="@id/battery_cluster" android:layout_width="wrap_content" android:layout_height="wrap_content" layout="@layout/battery_cluster_view" />
<FrameLayout android:paddingLeft="4.0dip" android:layout_width="wrap_content" android:layout_height="wrap_content">
<ImageView android:gravity="center" android:layout_gravity="center" android:id="@id/battery" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<TextView android:textAppearance="@style/TextAppearance.StatusBar.Battery" android:gravity="center" android:layout_gravity="center" android:id="@id/battery_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:singleLine="true" android:shadowColor="#ff000000" android:shadowDx="0.0" android:shadowDy="0.0" android:shadowRadius="5.5" />
</FrameLayout>
</LinearLayout>
<com.android.systemui.statusbar.policy.Clock android:textAppearance="@style/TextAppearance.StatusBar.Clock" android:gravity="left|center" android:id="@id/clock" android:paddingLeft="6.0dip" android:visibility="gone" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="true" />
</LinearLayout>
<LinearLayout android:gravity="center" android:orientation="horizontal" android:id="@id/centerclock" android:layout_width="fill_parent" android:layout_height="fill_parent">
<com.android.systemui.statusbar.policy.DateView android:textAppearance="@style/TextAppearance.StatusBar.Date" android:gravity="bottom|center" android:id="@id/date" android:paddingLeft="15.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="true" />
<com.android.systemui.statusbar.policy.ClockCenter android:textAppearance="@style/TextAppearance.StatusBar.Clock" android:gravity="top|center" android:id="@id/center_clock" android:paddingRight="6.0dip" android:visibility="gone" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="false" />
</LinearLayout>
<LinearLayout android:orientation="horizontal" android:id="@id/ticker" android:paddingLeft="6.0dip" android:animationCache="false" android:layout_width="fill_parent" android:layout_height="fill_parent">
<ImageSwitcher android:id="@id/tickerIcon" android:layout_width="@dimen/status_bar_icon_size" android:layout_height="@dimen/status_bar_icon_size" android:layout_marginRight="4.0dip">
<com.android.systemui.statusbar.AnimatedImageView android:layout_width="@dimen/status_bar_icon_size" android:layout_height="@dimen/status_bar_icon_size" android:scaleType="center" />
<com.android.systemui.statusbar.AnimatedImageView android:layout_width="@dimen/status_bar_icon_size" android:layout_height="@dimen/status_bar_icon_size" android:scaleType="center" />
</ImageSwitcher>
<com.android.systemui.statusbar.phone.TickerView android:id="@id/tickerText" android:paddingTop="2.0dip" android:paddingRight="10.0dip" android:layout_width="0.0dip" android:layout_height="wrap_content" android:layout_weight="1.0">
<TextView android:textAppearance="@style/TextAppearance.StatusBar.PhoneTicker" android:layout_width="fill_parent" android:layout_height="wrap_content" android:singleLine="true" />
<TextView android:textAppearance="@style/TextAppearance.StatusBar.PhoneTicker" android:layout_width="fill_parent" android:layout_height="wrap_content" android:singleLine="true" />
</com.android.systemui.statusbar.phone.TickerView>
</LinearLayout>
<com.android.systemui.statusbar.policy.KeyButtonView android:layout_gravity="right" android:id="@id/home" android:layout_width="wrap_content" android:layout_height="fill_parent" android:src="@drawable/screen_lock" android:layout_toRightOf="@id/recent_apps" android:contentDescription="@string/accessibility_back" systemui:keyCode="26" systemui:keyRepeat="false" systemui:glowBackground="@drawable/ic_sysbar_highlight" androidrientation="vertical" />
</com.android.systemui.statusbar.phone.PhoneStatusBarView>

It looks like you've used a dedicated center clock here ('com.android.systemui.statusbar.policy.ClockCenter') and that's what you want to put the date under.

To be honest, I think you'd be best to use the Best Method in the OP to center your clock instead. But, if you want to use the clock you've got now, try swapping:

<LinearLayout android:gravity="center" android:orientation="horizontal" android:id="@id/centerclock" android:layout_width="fill_parent" android:layout_height="fill_parent">
<com.android.systemui.statusbar.policy.DateView android:textAppearance="@style/TextAppearance.StatusBar.Date" android:gravity="bottom|center" android:id="@id/date" android:paddingLeft="15.0dip" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="true" />
<com.android.systemui.statusbar.policy.ClockCenter android:textAppearance="@style/TextAppearance.StatusBar.Clock" android:gravity="top|center" android:id="@id/center_clock" android:paddingRight="6.0dip" android:visibility="gone" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="false" />
</LinearLayout>

with:

<LinearLayout android:gravity="center" android:orientation="[COLOR="Red"]vertical[/COLOR]" android:id="@id/centerclock" android:layout_width="fill_parent" android:layout_height="fill_parent">
<com.android.systemui.statusbar.policy.ClockCenter android:textAppearance="@style/TextAppearance.StatusBar.Clock" android:gravity="top|center" android:id="@id/center_clock" android:paddingRight="6.0dip" android:visibility="gone" android:layout_width="wrap_content" android:layout_height="fill_parent" android:singleLine="false" />
<com.android.systemui.statusbar.policy.DateView android:textAppearance="@style/TextAppearance.StatusBar.Date" android:gravity="bottom|center" android:id="@id/date" android:layout_width="[COLOR="red"]fill_parent[/COLOR]" android:layout_height="fill_parent" android:singleLine="true" />
</LinearLayout>

You've duplicated your LGDataView..

Try:

<?xml version="1.0" encoding="utf-8"?>
<com.android.systemui.statusbar.SignalClusterView android:gravity="center" android:orientation="horizontal" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layoutDirection="ltr"
xmlns:android="http://schemas.android.com/apk/res/android">
<FrameLayout android:id="@id/wifi_combo" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="-2.0dip">
<ImageView android:id="@id/wifi_signal" android:layout_width="wrap_content" android:layout_height="wrap_content" android:scaleType="center" android:layout_centerVertical="true" android:layout_alignParentEnd="true" />
<ImageView android:layout_gravity="bottom|center" android:id="@id/wifi_inout" android:layout_width="wrap_content" android:layout_height="wrap_content" />
</FrameLayout>
<View android:id="@id/spacer" android:visibility="gone" android:layout_width="6.0dip" android:layout_height="6.0dip" />
<com.android.systemui.statusbar.NoSimView android:id="@id/no_sim" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<com.android.systemui.statusbar.NoServiceView android:id="@id/no_service" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<FrameLayout android:layout_width="wrap_content" android:layout_height="wrap_content">
<FrameLayout android:id="@id/mobile_combo" android:layout_width="wrap_content" android:layout_height="wrap_content">
<View android:visibility="invisible" android:layout_width="6.0dip" android:layout_height="6.0dip" />
<ImageView android:id="@id/mobile_signal" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<ImageView android:id="@id/mobile_type" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<ImageView android:id="@id/dsda_mobile_signal" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<ImageView android:id="@id/dsda_mobile_type" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<ImageView android:layout_gravity="end|bottom|center" android:id="@id/mobile_inout" android:layout_width="wrap_content" android:layout_height="wrap_content" />
</FrameLayout>
<com.android.systemui.statusbar.LGDataView android:orientation="horizontal" android:id="@id/data_combo" android:layout_width="wrap_content" android:layout_height="wrap_content">
<ImageView android:id="@id/type_info" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<FrameLayout android:id="@id/lg_data" android:layout_width="wrap_content" android:layout_height="wrap_content">
<ImageView android:id="@id/data_inout" android:layout_width="wrap_content" android:layout_height="wrap_content" />
<ImageView android:id="@id/data_type" android:layout_width="wrap_content" android:layout_height="wrap_content" />
</FrameLayout>
</com.android.systemui.statusbar.LGDataView>
</FrameLayout>
<ImageView android:id="@id/airplane" android:layout_width="wrap_content" android:layout_height="wrap_content" />
</com.android.systemui.statusbar.SignalClusterView>