I did this on a 6 month contract as an experiment over a mild winter in the UK in 2011. You can pretty much do this anywhere.

Couple of tricks:
1) Get a small camper/van that can park in one car parking space with a diesel heating system. Kitchen is irrelevant. Bed/toilet/heating system/space to sit and type/space for clothes to hang.

2) You need a toilet but usually you time your bowel movements to only need to use it as a urinal unless you decide to go for a crazy hot curry

3) Find a local sports centre (not gym) with a sauna. Go for a swim in the morning, spend the evenings working out or hanging out in the sauna (you get regulars).

4) Bank of leisure batteries in your van (to drive the heater and give your laptop power), can give you the power to live for weeks inside your van. Luckily I went home every weekend to recharge them. If you can't get a power source connection (friend etc.), then consider covering your roof in solar power cells.

5) Unlimited mobile data plan that allows tethering.

6) Clubs/Meetup/Work social groups (CRITICAL).

7) No it's not 'hot' to invite a girl back to your van in a car park.

8) Scout the areas and work out where to sleep. Sleeping on a road can mean you get traffic buzzing you from 5am. Go find a really quiet road or lay by. Use retail park car parks if they don't have security patrols. Remember you're parking up at work during the day. You only really turn up after the gym at 8pm or later and leave by 8am.

9) It's quite liberating. Want to wake up next to the sea and go for a swim....yes you can.

10) Be proud of what you are doing. The limited space you have frees you from clutter.

11) Do crazy things...like continue to run an ebay magic card sales business inside the van!

12) Cold is your enemy. When winter hit hard, the issue was the driver cabin and the rear doors. Two cheap double duvets insulated the rest of the van from those cold spaces.

13) Go stealth mode if possible. No windows on the sides of the van, roof windows are perfect. You want somebody to think there is no one in the van.

14) Layout can be interesting, but I prefer bed at back on a removable platform, storage under neath, rear door 'insulated'. Sliding door opens into a space with bench and toilet under bench. Blackout curtains between driver cabin and rear area. Lockable from the inside.

15) Always go for a van you can stand in.

16) Check your drinking laws. In the UK sleeping in the back of a van is legal if drunk.

17) Going to repeat this. Scout out your area and work out great un-disturb-able places. A quiet car park in the centre of town may have a lot of pedestrians walking through it at 2am going back from clubs. Go for those parks/spaces that are not natural through routes. You will get into a routine. You'll end up parking in the same place on the same night of the week.

18) Be social. Get out of that space. Do not go back to the van and lock yourself away and watch stuff on the internet. GET OUT.

[edit] This was the van: https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-xaf1/v/t1....

Slightly on the big side, but it worked at the time. If I was going to do it again, I would custom build. Height for me being 6'2 is always going to be an issue. I would consider a normal height van but bending over all the time is not my thing.