I tightened mine down as close as I could. It's surprising the hull has a slight convex there, as you'd think it would be flat. It did not affect my hinge action but I could not get it tight to the outside edge.
I sealed around the new holes and the old holes at the plate with 3M 5200. If all structural pieces break i'll still have the plate glued on to the boat.
I think I was pretty lazy in filling the holes in the hull. On my boat it's a little awkward getting to them from the inside. If I remember right I filled the old holes with 5200 and pushed a bolt in to fill the space with something solid. If I had sealed the outside well there would be no water there anyway.
Anyway, no leaks at all after three seasons.
The picture has the shadows lightened to give as much detail as I could.