Welcome aboard. Glad to see you took the bull by the horns
. You are more experienced than I so hats off to you. I did the same thing and purchased my boat without any sailing experience.
I have a product I am going to use on my deck to prevent leaking. I cannot post the link yet as I have to have a few more posts under my belt before I can copy and paste a link in the forum, but the product is called Poly Coat and is used in commercial applications for patio's and decks in high rises for total leak proof decking. It can be used on fiberglass and wood. I will share the website with you when Imam able.
Good luck with your project and welcome !!!!!!