The Fir(as you mentioned) will check so I'll cloth the 4 cockpit well sides, fill with a few coats, and paint. The sole you see is sized for a 1" 'grub' around the perimeter that will join the well sides-with epoxy and screws for the final install(after binnacle, pulleys, manhole, emergency tiller deck plate are cut, bolted-and removed). All these holes and their parts will have to be well bedded.

I can't see good reason to cloth the sole. It will be slathered in epoxy when the deck goes down. I expect the caulking to way outlast my owning the boat and the existing 1/2" plywood under the 54 year teak decking is still in good shape. Further, they didn't glue it down, instead, it's screwed from below. The 3/4" is already stiff without the 1/2" decking addition(that will span the beams below for added stiffness).

As far as the trapazoid tops, I think I will end up just going with a taper on the decking where it meets the outer frames, and no cut into the margins. I prefer the cleaner look and if the ends are glued in epoxy, that appears to be fine. I don't think I can figure the pattern-margins, etc. for the decking, until the have the decks and lids mounted and hinged. It looks easiest to do in place. I'm trying to stay away from any margin boards that are wide. That's a little tricky in some areas, especially outboard of the trapazoids where the coaming bulges outward.