The one thing I didn't hear mentioned was a ball of dumm dumm, or permagun as RV shops call it. It is a great sealer and will seal just about anything until you can get home and seal it correctly.
About fifteen years ago I had a friend that was a cop make a short trip with us and one night as he was removing his gun, it accidently discharged and shot a hole in the roof. We climbed up there via a step latter we borrowed and filled the hole with the dumm dumm and it never leaked a drop of water. It was about six weeks later when I made a permanent repair.