Jb weld and marine tex gray have both done the job you describe. My thought is to leave the boat rigged and gain access to the bad areas. Prep with a wire wheel in a dril or something else suitable and spread the weld material in a small area around the hole and put a piece of packing tape over it to keep it from dripping or sagging. If you can remove the tape easy when done that would be great. I’ve sanded JB with a square vibrator sander to smooth it out and then go fishing.