I thought it would be obvious to epoxy the inside before the deck goes on as well as glass tape on the chine and keelson. I also epoxy the inside of the deck sheet before fitting it. That means everything is covered as it is all visible and easy to get at. The decks go on, held down by straps and sometimes staples. They are then cut back to level with the deck and glassed on the seam only.

Admittedly my oldest kayaks is only 30+ years old but I presume it will last a bit longer, another decade or two.

As for whether your epoxy is any good. If you'd mixed some and left it to dry overnight while asking the question, it would probably be answered by today.