Be careful using a pressure washer on trailers. Don't go at it like you do your vehicle. The pressure can do a number on your decals, on all your electrical parts or switches, etc. Some use a home pressure washer but they typically have less pressure then the commercial places.
I have gone away from a pressure washer and just use my garden hose and a brush now.
2011 GMC Sierra 2500HD
2014 Rockwood 8289WS, Diamond Pkg.