This shows a trapazoid lid. The decking is simply tapered to the frame on the lid. I plan to keep the frames aroudn 2 1/4" and the decking @ 1.5" for contrast.
I intend to use butt hinges like these. Because of the thickness of my lids and their build, the only good fastening is low in the 3/4" plywood. The nice thing this cockpit has is a straight coaming. I've got at least a 2" bulge in roughly 4' long lid area.