Newbie; I’m not even sure I’m texting in the r

Granddaughter in a make-shift hammock type bed above the dinette bed? I don’t plan to ever use it as a dinette- my 1955 Shasta has an original canvas roll out cot type bed with 2 horizontal large dowel rods, horizontal-
I would ONLY trust answers from R-Pod owners. Is there a vertical support inside the wall? OR
What if I used Plastic PVC & built a frame that would set on the edge of wood under cushions

Rpod walls are very lightly constructed.

There are a few thin wall aluminum box tubes in the walls otherwise it's just thin plywood. So I wouldnt try to hold up a cot on the walls.

You could bring vertical supports down to the floor (not the thin plywood supporting the cushions). I would use probably 4 wood posts, not PVC which is too flexible, and I'd also add say some 3/4 inch plywood under the posts to spread out the floor load (the floor is pretty lightly constructed too, everything in rpods is in order to keep them light and cheap to manufacture). The problem you'll have is the posts will try to rotate inward when you put weight on the cot, so I'd suggest cross braces between the posts to prevent that. Basically you'd be making a box frame which you could then just put a piece of plywood on and a foam pad as a mattress.

My $0.02 for what it's worth.