I had some damage to my trailer last year and had a friend repair a (large) hole with bondo, sanded and then he used primer spray paint. Then to finish, a few coats of white spray paint. Then he buffed it with a car buffer on a drill, I believe.
It turned out great!
I posted the pics on here. Not sure where to look, but if you search my name you should come across them.
EDIT: Here's the link to my original post with the pictures..