In general the hole behind the light should be at the center where there is sufficient foam compression. If you believe there is a problem I would suggest cutting any protruding gasket material off, carefully, with a razor knife, then putting down a thin bead of Parbond along the top half and front exposure of the light. I would use masking tape to get a controlled bead. Done properly, it's fairly time consuming to perform.
To learn to see below the surface, you must adjust your altitude