Have fun with your project!
I suspect the reason you don't see too much variation in exterior colors (mostly shades of white) is that white is best to counter heat buildup inside the trailer. Since there is a great deal of open space inside a trailer and there is very little insulation, the Air Conditioner has to work almost full time if you are camped in a hot, sunny location. A dark color would just make the problem worse.
But, you could paint the outside ANY color that suits your fancy.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew