OK, let's get it straight.Is China proper a political term or geographical term ? If it is a geographical term, there is no way to include taiwan in China proper because TW is a island far from mainland.  
If it is a political term , there is a term used by qing empire called "內地十八省",
which means "inland 18 provinces". Here is the proof:
http://edu.beida-online.com/data/data5.jsp?db=sanjiao&id;=gejx18
(sorry it is the same link but  a short while ago I didn't translate it right.)
但有時卻只指傳統的“中國”范圍，即內地十八省，而不包括蒙古、西藏、青海、新疆、東北和台
灣在內。
translation:sometimes "china" only means the traditional area of china,which means 
"inland eighteen province".it dosen't included mongolia,tibet,qinghai,Xinjiang,manchuria and TAIWAN.

Here I have to emphasize the word "inland", and that's why the Qing officer didn't consider taiwan as part of the traditional area of china.