Pretty much any boatyard could shoot your finished trailer with AwlGrip — 2-part LPU yacht paint. Paint job would last for years.
https://www.awlgrip.com/Any decent auto body shop should be able to shoot it with 2-part automotive LPU, too. Something like DuPont/Axalta Imron
http://products.axaltacs.com/dcat/us/en ... ality.htmlYou do want a pro to shoot it, just because you're talking at least $150 – $200 per gallon, they need to use the right primers/tie coats for the substrate. And it's way toxic (cyanide gas is a byproduct of the curing process for starters.)
They come in a rainbow of colors, stock. And they'll both do custom colors if you'd like.
Another option would be System 3's water-reducible LPU. Still $160/gallon, but much easier for an amateur to apply. It can sprayed or roll-and-tip. Color selection is more limited.
https://www.systemthree.com/products/wr ... ne-topcoat