Wooo, New SeaCraft owner here :-) and boy do i have a project.

[FishStretcher]

Poplar plywood for the deck? It isn't quite clear from your post.

I have ranted about plywood in fiberglass boats before. I say things like it is heavy, wicks water, and is a termite hotel. I'll leave it at that.

Maybe you can get foam for a better deal than I can? I would suggest it. It is expensive, but you will buy a lot of resin and glass, too. Balsa seems to hold up much better and be lighter than ply, too. If I didn't do foam, I would do balsa before I did plywood due to the grain direction and density.

Good luck! It looks like you have a good start, some help and a great workspace.