The pictures don't show the bulkhead framing. But it is Typ. 1"x 2"( real size 3/4" x 1-1/2") Clear grade wood. The 3/4" depth or void between the bulkhead frame studs and top rails must be Fitted and Glued; Laminated, with (7ply min.) plywood, to the back of the1/4" 3ply paneling.
I Positioned the Lagun mount Plate holes to align with enlarged (to fit Lagun bolts) Chrome Shelf bracket holes.