One of my buddies ran something like that in his pickup for a few years. it worked. As for an SUV or a pickup with a shell, If your looking at the type that connects to the back or side, I would suggest a regular tent unless you plan on folding it up every time you want to move the truck. If your moving spot to spot anyway, both have to be folded up.
My buddy only had one regret, wind. Due to the way his was built, the wind effected it more than a normal ground tent. His situation was, he couldn't run a shell and his Jeep was on a trailer. That kind of killed anything outside of a tent.