Building a climbing wall for my kids out of a disused stage piece I got recently. The stage piece is 7 tall by 4 wide but 10 inches thick (with 3 cross members spaced 20 inches apart). Its a stout chuck of 3/4 inch ply (and its heavy...200 lbs maybe?) and can easily hold a climbing wall...but...I have NO idea how to mount it to the wall. The studs are 16 inch centers which is great for a 4 foot wide wall except i I can’t just buy 15 inch screws and jam it into the wall. Any suggestions on how to get it on the wall in a solid way? No, I can’t take the top sheet off, its glued and stapled exactly 2342 times.