I would research this a bot further before you start spraying epoxy paint. If you have exposed aluminum you need to use a self etching primer, this will be a two component paint. Some older trailers the metal mfg used basic enamel paint. If you attempt to cover enamel with epoxy paint, such as an Imron or Jet Glo your going to have one hell of a mess on your hands, paint will blister and peel. In other cases materials may have been powder coated, in which case you can prime and cover with Imron or Jet Glo.
In terms of aircraft paint, probably overkill for a trailer, you can get automitive finishes that are very good at half the price. If you want aircraft quality, look at Dupont Imron, JetGlo or Randolph paints. You can find these at Aircraft spruce or Chief Aircraft. You'll need a spray booth with filtering if you want a quality finish otherwise it won't look that great.