Here is something that might work. You attach the truck and topper to the tent and make it one open area. I have been looking of the same thing, but perfer to have a open floor changing room since I plan to sleep in the bed of the truck, and cooking/playing cards/standing in the tent.
a cheap one:
http://safetycentral.com/telosqdotemo.html
couple of fancy more expensive options:
http://www.familytentcamping.com/site/1406228/page/1133735
a cheap one:
http://safetycentral.com/telosqdotemo.html
couple of fancy more expensive options:
http://www.familytentcamping.com/site/1406228/page/1133735