If you didn't wax a new RV for 5 years it would still look ok anyway. All he is doing is putting on a decent coat of synthetic "wax", which you can do yourself in 4-8 hours, depending on the size and how many breaks you take. Or hire somebody to do it for $125-$200, depending on your area.
Ask him what happens if you come back in 4 years (assuming he is still in business) and say you aren't happy with the shine? What is he promising for that extra cost?
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC