Well, I don't want to burst your bubble but if you simply ground out the bad gel coat as it's shown and filled that corner with one of your "bondo" products you're asking for future failure all along the edge. IMO the repair of that corner would entail grinding away the gel coat at least an inch back from the edge, then grinding into the base fiberglass ~1/16" to 1/8" deep tapered back to good material, then laying in layers of glass mat & resin to re-build the corner and topping it off with a skim coat of quality filler to level. I don't care what material you used, if you bonded to gel coat you're asking for trouble. That said, it's just my opinion and you've never yet asked anyone for advice here that I recall, so I don't expect that you really care about my opinion anyway.