I thought I should take a second to update this thread with project progress. Going well so far, I think. The livewell hatch was paper thin, and as the photos show, I learned a lesson about running through it from the back. 8^) In the end it looks good with two coats of factory gelcoat and some wet sanding. I'll polish it up when I do the rest of the upper...
Deck hatch was amazing. SO heavy, and once pulled up it pretty much fell apart in my hands. To clean up the big one took 10% of the time it did to clean up the small one. I got lucky at the fiberglass supply place, as they hooked me up with a layup of 5/8 tan foam with 10 lb glass that they did for a demo. Perfect material that would have cost a lot otherwise. I spent enough time to make sure that the steel work surface was flat, so tonight I'll put a mesh and a rove on the underside and call it done.
Thanks for all the advice so far. Much appreciated.
So, next question is what techniques have you used to reestablish the screw backing? I removed the lightweight members that cross the fuel tanks, and will dial in panel elevation with the replacements (foam and glass, no more wood). But what did you install to catch the screws?