Thanks for posting. Not only do you get to vent, but you also give the rest of us information on improving techniques that we can use. Certainly it sounds fixable. In a case like this it's best to do the best you can with what you have. Sounds like you are doing just that. As for where you have to resand I don't think you'll have to do the whole deck...BUT....you may. Sand a test spot as you need and recoat with epoxy. See what happens. If it's not satisfactory then you can sand the whole thing. I always fiberglass before removing from the forms. I also have never went stapless using hot glue. I don't think I will.