Colin,
I worked for Ala Wai Marine in Hawaii for a couple years mainly repairing fiberglass boats after people would bounce them off the reef, the dock, logs,each other..................business was brisk!
You are doing everything right.,but make sure once you have it good and stable from the back, grind out a shallow "v"recess at/along the break through the gel coat and fill with mat and resin ,dont worry if it looks like hell when your done you can just shape it up with your "d.a.."when hardened
And try the left lane at your next final
