Here is another vote for a pipe lining for the holes. I made the ones for my Pygmy Goldeneyes out of epoxy and glass. I wrapped a 5/8 dowel with plastic kitchen wrap then a strip of epoxy saturated cloth that gave it about 6 layers of glass then more kitchen wrap. I baked the pipe the speed the curing and it shrinks the dowel making its removal easy. The kitchen wrap is removed and the tubes epoxed into the hull.

I glassed it into the boats before adding the deck. Pygmy instructs to do the end pours before the deck is attached. I added scrap cloth into the end pours and wrapped some around the tubes to tie it all together. The end pours are easy to shape and reinforce with glass when done before adding the deck. Only the the underside of the deck tips are not reinforced. If you worry about this a small end pour could be done after adding the deck but I don't think it's needed