Callen's being steel framed would be scooped up. An aluminum model could be an option for smaller trucks.
A Callen style with a VW pop up would be on my truck in a heartbeat.
Dylan,
The Cave Camper looks very nice and well built, but for me personally I don't see a lot of reason to go with the Cave Camper @ $10K over just a standard truck cap. It appears all you're getting with the Cave Camper over a truck cap is the ability to stand and better insulation. If the heating and cooling was added along with a 2 burner cook top and a small refer for not a whole more $$ I would give it a hard look.