I have been reading this forum for years and tonight realized that for the first time I may have some info that may help some of you.
A few years ago I was having problems with stripped screws. I could not get some screws to stay in stripped holes in my fiberglass. Well my neighbor (who is an airplane mechanic) introduced me to threaded pop rivets. They are great. You insert a stainless steel rivet and then insert a machine threaded screw. It is the same principle as anchors you would put in stuff like drywall. They are very stable and you can remove and install the screws as much as you want.