You could pretty easily cut a small piece of 1/8″ aluminum plate and match drill holes with the ram ball before mounting to the boat. Then you would have a nice backer plate to reinforce the fiberglass and help distribute the load. Use stainless machine screws with a flat washer and a nylock nut on the underside, you should be good to go and not have to worry about it loosening up over time. After the first trip out, double check, but should be good after that.
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