I know Nick say's to make them flush and tape them in but you need to compenstae for gasket thickness. No matter what you use for a gasket you need xtra space. I have been using a piece of cardboard on the top side of the hatch and making it flush with the deck. So when you look at the inside of the deck the hatch sticks up the thickness of the card board. I also have switched to using saran wrap wrapped around the hatch to act as the release. I find it works better. You don't need to woory about getting it out when the epoxy sets up. The kerf gap should be filled/sealed to prevent epoxy from leaking in.