Our walls are drywall on 2”x4” studs 60cm apart.
I would cut a circular hole from each side between two studs, i.e. 50 cm diameter. That would give me two drywall discs that I would save for reconstruction.
When it’s time to undo, I would make two pieces of 2”x4” short enough to get into the hole and fix them to the drywall, and possibly the bottom joist or something. Then I can reattach the 50cm discs and cover the gaps with plaster or something. Then sandpaper it and paint. Should be good enough.
Sometimes I’m too optimistic, and that’s something I’m working on improving. See my other goals. But this one I think I could handle.
The beds are less of a problem, if I build them myself I could modify them, or I could sell them second hand and buy new. I could even use them as kindling.