I have made four Outer islands and use the VCP hatches. They have polyproplene female inserts which I bond to striper decks from underneath. I rough them up with 40 grit paper and epoxy them in place. It's a mechanical bond but one of my boats is 7 years old and that joint has never failed. The VCP's come with indentations for drilling out for screw holes. I drill them out so it almost creates epoxy rivets as well as the bonding of the flat surfaces. I also run a fillet around them that actually goes over the top (in my case under side) edge.

When I say rough them up good - I mean it - they are scratched and scored deep. Because my inserts are on the underside, I can really slop on the epoxy fillet too.

They are still my favorite hatches because I can always leave a t-shirt in there and roll for hours and it will be bone dry - and I can pop them off in a second. Of course, everyone has their own sense of esthtecis.