Burro door repair question

[Sue and Henry]

I had problems with the burro hinge and latch this summer. We travelled with a roll of duct tape supporting the problems.

With tons of help from my friend and neighbor, Albert, the door has been cut at the hinge location on the narrow door edge position top and bottom. The wood has been mostly removed and we have two very thick aluminum plates (shown in the photo) to fiberglass in as a door hinge screw solution. (3rd photo)

I've also sanded down the door frame hinge area for re-fiberglassing. The inside of the frame was also opened and fiberglass and 6 gauge aluminum has been put in place to strengthen it. Now that I've sanded the outside for re-fiberglassing a sunken area at the hinge position, I see some problems. (1st photo is inside 2nd photo is outside -- tap on the picture to see the enlargement showing the problem)

My question: sanding off the gel coat and (I think) paint from the outside wall, the fiberglass is paper thin and I can see vacant pits. Is that a quality control issue in that specific area or do you think there were repairs thinning the edges in the 32 years prior to my adoption of the burro? I do see other areas in the door and frame edge that appear to have similar problems.