My two cents worth.
The upper bunk is two pieces, one that you can see when the bunk is in the down position and another that is stored behind it, and is used only when the bunk is up.
The cushions on the lower bunk are different than the standard 17 B cushions. The standard 17 B cushions will not allow for raising and lowering of the table unless the center cushion is removed and stored.
On my first generation 17 B, the bathroom and wardrobe walls are not strengthened beyond that of a standard trailer. I attached a file that shows the bunk in the up and down position. This shows the small metal plates that are attached to those two walls to hold the bunk in the up position. These metal plates are attached to the vertical supports in the corners of those two walls.
The wood that is bonded to the front wall of the trailer was installed with a fiberglass over wrap to attach it to the wall. Adding this fiberglass, would require a bigger hole to be cut in the front fabric, larger than just a size for the piece of wood. You may choose to not use this overwrap and directly bond the wood to the wall, but this would not be as strong.
Perhaps you could cut the wall cover material below the hinge line for the bunk for installation of the wood support. This would keep the seam from being visible when the bunk is down.
The metal support arms were made by ETI and they sold a set to me because I was not adding the bunk, I needed the support arms to make a safety rail for the upper bunk.
Best of luck on your hunt.
