How to repair delamination

I knew an old gentleman couple of years ago who had one spot of fiberglass delamination in his motorhome. Don't know exactly which epoxy he used but know it was very thin, for he took a small-needle syringe, drilled a tiny hole in the middle of the bad area, and injected epoxy into the hole. It happened to be near enough window he could get a large C-clamp on both sides, so he clamped the area as tight as he could; never a problem since, and the area flattened out where you don't see it at all.
His problem was strictly localized, the delaminated area approx. 12 in. dia.