Starting sketch

I used the original sketch-up tool - pencils! so please forgive me if the drawing is a little crude. There will be 3 of us camping, so figured I'd need to design something suitable. Saw a slide out type TD, but I think that's waaay too complicated so after looking around some, came up with this. In case it's occasionally two, I want to make the "bunk" bed removable. And yes, there will be a door on both sides, just left that off on the drivers side in the sketch.
My idea is to use 3 or 4 bed frame rails cut to length that set in slots on wood support ends (that will be framed to rest on the floor, not just attached to the walls). 1/2" or 5/8" ply on top of the bed rails and an air mattress on top of that. If we're using it for two, the ply and rails can be stored under the main mattress and the air mattress just stowed away or left home. No need to mess with a big foam piece there.
I'm using a boat trailer, so I can extend the TD body as needed, height as well. I'm probably going for 6' wide for the bunk to be usable (our son is 13 and about 5' 6" now). Height wise - 8" main mattress (queen - foam sections), 18" of leg clearance to the bottom of the steel bed rail, then about 8" of bed rail, plywood and air mattress or 34" total, say 36" with bedding just to round up. May go 5' 6" or 6' high so there's room to get in and out and maneuver around some.
6'x6'x12' is probably stretching the "teardrop" idea some, it's more like a full on cry
but if I'm going to build it, gotta meet the need.
Thoughts or advice greatly appreciated...
My idea is to use 3 or 4 bed frame rails cut to length that set in slots on wood support ends (that will be framed to rest on the floor, not just attached to the walls). 1/2" or 5/8" ply on top of the bed rails and an air mattress on top of that. If we're using it for two, the ply and rails can be stored under the main mattress and the air mattress just stowed away or left home. No need to mess with a big foam piece there.
I'm using a boat trailer, so I can extend the TD body as needed, height as well. I'm probably going for 6' wide for the bunk to be usable (our son is 13 and about 5' 6" now). Height wise - 8" main mattress (queen - foam sections), 18" of leg clearance to the bottom of the steel bed rail, then about 8" of bed rail, plywood and air mattress or 34" total, say 36" with bedding just to round up. May go 5' 6" or 6' high so there's room to get in and out and maneuver around some.
6'x6'x12' is probably stretching the "teardrop" idea some, it's more like a full on cry

Thoughts or advice greatly appreciated...