Thanks, yes, just plywood. I first used a too thin one so it bended, increased thickness to 9 mm, but still bending a bit so put some metal reinforcement beams on the back. Seems quite some strong forces on such a hide, perhaps because still drying.
For the hide on the back I put in (plenty) small eyelets and a screew into the plywood to hold it.
For hanging I put a stell wire through holes I drilled in the reinforcements beams, joined the wire in a loop with wire rope clips. A screw in the wall, and it is just hanging like a painting.
Wonder if this is clear. If not, get back to me and I will try to clarify.