If you are absolutely set on using a neoprene or interlocking gasket and not the silicone/urethane approach the gasket recess can be formed similarly to the previous method and still accomplish a flush hatch. The idea is that the compression of the gasket can be taken into account at the point of attaching it(glue thickness or offset thickness) after the recess etc. has been made.

The assumption is that the gasket compresses only slightly. This is more true the more evenly spread the hatch attachments, so take it into account if fewer are used. So:

Cut out the hatch and glass the deck and hatch. Glue the gasket to the hatch. Cover the gasket w/ vaseline and saran. Tape the hatch in place, but raised say 1/16" at the compression points. Glass the flange right over the gasket, carefully making the fit as well as possible. ( some use of 3/4 oz cloth?).

Voila! Works for 2 part gaskets too. Make flange as before but w/ lower part attached to glued upper. Strip off saran and glue lower gasket half to the flange. Perfect.

To replace w/ new gasket, put gasket( with glue on top) in track in flange, press on hatch, let set and you're back to the beach.

-mick