We've used Knead-it & JB Weld to fill holes in an aluminum boat where the rivets came loose & leaked. We knocked the rivets out and filled the holes and they held for a long time before the holes in the boat were welded closed. Also used a bolt/nut/washer/silicone as an emergency patch for a rivet that came loose while we were on a fishing trip & didn't have any Knead-it or JB Weld handy.
Either one will work as a temporary fix ... but, if bolt/nut are used, be sure it's not where the boat bottom comes in contact with the trailer skids/carpet.