The cleaner that I use to clean the RV work great. It is "Totally Awesome" and I buy it from Dollar General. It melts black streaks right off both the fiberglass and the aluminum skirting.
When I just wash it I will use a wash and shine product just to take dust and normal dirt off.
I wax the RV twice a year and used Nu Finish. However I have been using Meguiar's Hybrid Ceramic Liquid Wax on the truck, and will be changing to that on the RV as well.
https://www.meguiars.com/automotive/...ction-easy-use
My truck is about 10 months old and I wash and wax it a lot.