This one has 9mm ply webs on each side against the solid wood which will form part of storage dividers and also support the double berth in the front. You can see them below, they were cut oversize and then after clamping the solid the ply was marked for cutting the curve.
Then the solid wood and ply were epoxied together, clamped to hold them flat.
Now the sides were solid, the frame was placed on the lofting floor, propped up and had the hardwood cross piece screwed ( 14 gauge x 40mm) and epoxied together. A temporary cross piece was screwed across the top to give it support and also for placing on the strongback upside down.
Below is the rear face, I had some epoxy left over so coated the ply each side a bit up from the solid wood/hardwood cross piece. Width at the top to outside 2340mm.
Close up of the right rear: