If it's only a few rivets, I'd use my mini-grinder and a wire wheel. When my tinny leaks, I put the trailer and boat on a dry concrete driveway, fill it with about two inches of water and wait for the wet spots to appear on the driveway. I mark them, empty the boat, flip it over and apply JB Weld around the leakers, after cleaning around them first. No need to use heat or chemicals, either of which might cause further grief.
I'm an Eighth Day Adventist. On the Eighth Day, God went fishing!