Not sure about adding the wood plugs, which can still get wet &/or strip. You can just fill the holes with the thickened west epoxy & drill a pilot hole for the screws directly into it. I also use a dremel to spin a small piece of coat hanger, bent into a small right angled hook, around the inside of the drilled out 3/8" holes under the glass. This cuts a groove in the foam or remaining wood surrounding the hole, underneath the fiberglass skin. use a toothpick to make sure this shoulder will fill with the west epoxy as you fill the hole. This will prevent the epoxy plugs from being pulled up by the force of the screws. I think I refit every screw on my 1967 Nauset this way & the railings, seats & console never loosened again. LOL, find me a fifty plus year old whaler with rock solid railings. I even fished it with a down rigger clamped directly to the side railing for years. I did this to replace all several hundred rivets holding the rub rail to the boats perimeter also. that was time consuming to say the least! Very effective repair, but I think the undercut shoulder cut under the glass is essential.