Matt is right on regarding the structual strength being at the base and the deck surface. I've done the repair at the base and did need to cut in inspection ports for access. Pain in the butt to get to everything but it can be done.

You could simply be seeing stress cracks in the surface gelcoat. If no water is seeping into the hulls you can probably ignore the surface cracks. My 17 has a few gelcoat cracks around portions of the deck hole and a few inside the sockets but no leakage.

Good luck, Tom G