I’m not sure if it’s the most common way but it was the easiest for me to think of. I used two coats of Epoxy on the 2X4’s. Then when I drilled into them to install them, I dabbed Marine 4200 for the holes and dabbed 4200 on the mounting hardware. The deck is solid in itself without the fiberglass I’m going to lay.Nice progress! Is the fastened 2x4 ledge approach for the tank hatch the most common way to reinstall the cut hatch? Did you screw the cut hatch into the 2x4s?
I screwed down the cut hatch with 2” stainless screws. Tapered the holes to hide the screw heads. Covered the heads with epoxy. Measured the screw holes and logged the measurements if the fuel tank ever needs to be replaced again (hopefully never but maybe 20-30 years from now). I’ll be dead by then.