I bought a soft bristle brush from my dealer when we bought our Northpoint. Works great, however I found this one that'll work better with having side bristles on it.
https://www.amazon.com/CarCarez-Bris.../dp/B01EHD6YP0
It's just as soft and doesn't hurt decals.
The wash I use is a Wizards brand, but any good name brand car wash will work just fine.
Wax, I use Wizards Shine Master and for a quick hit before we go, helps take the bugs off much easier, I use their Mist and Shine. The Wizards wax is safe for decals. Our trailer gets washed after every use and waxed once a year. Waxing it is a BIG job.