I could have used something like this many a times when it rained or even was hot out. It gets you off the ground when it rains or catch a WELCOME BREEZE in the summer time. Caught this on the SEMA Show website from Las Vegas.
http://www.cascadiatents.com/Photo_Gallery.htm?m=66&s=546

Yeah, but if you really think about it, then you can't move your truck.

alot of older jeeps came with the option of the tent, not sure about the newer models though