I’ll start by saying that you’ll use more resin, epoxy or poly, than you think you will. I used cabosill(spell check) as a filler for the poly resin I used to stiffen it and act like putty. I’ve seen floors attached to stringers with a layer of bondo or tiger hair on top of the stringers, apply the treated wood floor and used stainless screws, enough to hold it til the boding agent hardens. Then scuff the edges and fill any gaps with the thickened resin and add a 4 or 5” strip bonding the ply to the hull. Then cut and resin in a layer or two of ounce and a half chop mat, adding to the wall/floor transition in the process if you want. With this as a floor you shouldn’t have any issues with it til you’re tired of looking at the boat. The woven mat is strong but doesn’t flex for the transition from floor to wall.
Another option for the seat bases is to install the floor without these and plan where to attach them. Then treat the wood and either glass them top and bottom or wrap them with the flooring you used everywhere else, maybe with 5200 around the edge to seal and bond.if you glassed them you could paint them however you chose. The idea is to spread out the footprint and remove as much leverage possible. I used 1/4” aluminum and spread the plate between two crossmembers on the floor about a foot to 14” wide. It never wiggled after that. The seat bases I used had a 2” pipe and base that was about 10” across. The skinny posts we use on decks aren’t made for use while under way but I’ve seen them used for that. I have no faith that they would last.