Inquiring others who may have built a DIY camper on the 6.5 bed.

My 2005 crew cab has a 6.5 bed and a nice window at the back of the cab that needs to be incorporated in my build. As I have the carpentry skills and I'd like to stick with the lower 1,200lb weight suggestion. I'm going with a lighter weight design. Maybe an aluminum frame with 2x2 pine stud cross members, a thin insulated wall and sticking to the 63" width makes sense to me. The cab over would be only 5' X 63" dimension to enable this 6 footer to sleep diagonally while my wife, if she prefers, can sleep in the rear seat or on a folding bench seat on the bed. If she sleeps in the cab my border collie must have full run of the vehicle as long as she leaves the rear window open. If she closes it with the dog on her side, she may lose the battle as Rio rules the roost. Any ideas on a good closure to keep the weather out in the joining of the camper to the cab?

1,200 to 2,000 pounds isn't much after I load in the kitchen sink and a composting toilet. No black water, fresh water and gray water tanks will keep the weight low.
The camper will have to be 6'2" in height, so it might be a little top heavy around the curves going into Yosemite.
At what point is a super spring above axle advisable?
Thank you.

 

Welcome from LA (Lower Alabama)! That sounds like quite a project. You will got a lot more responses, and probably more helpful info, if you create a thread in the appropriate forum: https://www.tundras.com/forums/tonneau-covers-caps-and-shells.68/

Good luck with your project!