We just got a new Toy hauler and saw someone else in the Toy Hauler forum asked the same question I was wondering about. I have been told there are lots of things we can use that don't have to be bought at a RV store to clean our rig inside and out. Lets start a list and I will combine it and make a list on the subject.
Something I was told by the great guys at Innovative RV where we bought our unit was. When we got home and got it cleaned of all the bugs and road grime to take Orange Power Pledge and a hand towel to get it really clean . It leaves a wax like coating to protect and helps get the bugs and the black streaks wont stick.