If there is a Camping World in your area take it to the "RV Spa"
Pamper your RV with a day at the RV Spa - Camping World. They have packages and you can see the pricing at their website. You also get 10% off if you're apart of the Presidents Club. If you plan on taking it into them often it may just be worth it for the savings.
Or you can google in your area for detail shops. You'll be surprised at how many will detail RV's even though they mainly advertise themselves as auto detailers.