Do you know anyone in the aircraft industry? ie maintenance/manufacturing? You could use what is called a nut plate, or floating nut plate. If you had enough of these in place, it should hold. They get riveted into position. You would have to use a blind rivet, or huckbolt if there is no access to the bottom area. With a nutplate, you can remove the bolts, and the nut plates stay in place. Shreveport has serveral aviation businesses. You might talk someone into scoring you some 1/4" nutplates, and have them help you install them.
There are many "Blind" type fasteners in the aircraft industry. I will look in the shop and see if I can find some that will work for you. Are you fastening into fiberglass? How many fasteners are needed? Some of these types of fasteners cannot be removed once installed other than drilling them out. Would that be a problem?