Rough fitting of new door handle. Not quite totally finished but it worked out well. I cut rough opening for the new handle, then filled the remainder of the old hole with pieces of plywood. Then I filled the holes with low expansion spray foam and let dry. Then I trimmed the excess away with utility knife, leaving the same thickness as the original
fiberglass. I did the outside patch first, then sanded the crap out of it. Less is more when using resin. Then I removed all the spray foam that was left and then laid mats of
fiberglass on the inside, I used small pieces of Box to hold the mat up to keep it from sagging into the inner part of the door. Then sanded for ever again till smooth and cut in the new handle.