What I see most people do when they turn a smallish vehicle into a camper is build a plywood platform to put a mattress on and then either slide rubber-maids under it or just make a big honkin' drawer that slides out. Is the picture in your post your jeep or just something similar? Depending on the size, you're gonna have to yank out your passenger seat to make room.
https://www.youtube.com/watch?v=nG4M2Vfhdo0This guy has a pretty nice setup, but his is more for long-term living rather than wilderness trips. For a cheap camp axe, I would recommend the Cold Steel Trail Boss. It's nothing especially nice, but it'll last you a good while and preform just fine.
