Finally finished my hatch! A piece of MW in the front slides under the combing and keeps the front in place. Used epoxy and microballons to secure that wire.
Rear is held down by 3/8 rare earth magnets. 2 glued on the hatch at the end of the horiz balsa support and two glued to the hull. The magnets are supported and piece of 1/64 ply in front of each and they seem to have plenty of holding power.
Magnets assemblies on each end. Constructed the same way those that are glued to hull side. On my original Drake II, the magnets could contact each other when close (SLAMMED!) and somethimes the magnet would come loose and have to be reglued. I used this method on my LT-25 and it works well.