Sell paint for a living these days, Industrial blaster painter in another life, and I think for the average Joe the best paint by a mile is Killrust epoxy enamel.
Be mindful though not all the Killrust branded gear is epoxy enamel. The Hammer finishes ain't and nor are any of the satin finishes.
I use the Gloss black under the camper and the tug even under the arches, magic gear gets absolutely smashed on Pilbara stone a gazillion k,s across the central rd,Goldfields ,Kimberley and hangs on superbly. Best bang for your buck, get it most places, safe to use at home and any mug can use it, spraypack, brush or cheapo conventional spray. You can even put it on without priming on well degreased oranged black steel and it will not move!
Catalysed urethane's, Acrylic enamels, polysiloxanes etc etc all great products but unless your in the trade, got the gear and all the rest its pretty much out of reach for most.
The other thing to note is that very few trailers are built with anti corrosion in mind. Poor design, engineering and construction contribute substantially to your pride and joy turning to a pile of ferric oxide. Stitch welding, inappropriate fixings, thin galv coatings lack of seam sealing etc in many cases will not allow full coating of the painted area making failure inevitable.
Do your prep and seam seal everything , check your fixings to ensure that you are not promoting a cathodic point for dissimilar metals and make sure you put sufficient film builds on particularly on edges and corners according to manufacturers directions, ergo read the bloody instructions!
Cheers Mike
