I'm in the market for a truck camper and have a basic question: Why would someone choose a clamshell-style camper (e.g. Alu-Cab) over a full pop-up (e.g. Tune)? I guess the clamshell designs are a little easier to open because you only have to push up one side, but the full pop-up style has so much more room and better access to the sleeping area, plus they aren't that hard to open. Obviously a lot of people buy the clamshell style, so what am I missing?