Greg,
I don't know If I can help with your question I'm not a pro. at RV cleaning, waxing for a living, but having been an RV for the last 12 years, and having helped many of my fellow RV'er friends maintain their rig's all these years, including my own 34' 5th wheel (gel-coat), maybe these points might help.
1. Today motorhomes are clear coat paint. A friend and I cleaned, polished, sealed his 40' motorhome ($350,000 rig) in 8 hrs. (1120 sq ft of surface) Now keep in mind we do this every 6 months, so it was in good shape.
2. When you quote 6-10 bucks and hr for your effort, the question of what condition is it in IS A MUST!! ask any pro detailer who does cars for a living and he will take one glance at a car and knows what the condition is and what he's about to get into and most important, what it should cost.
3. Now, Trailers, 5th wheels. Gel Coat is a totally different anminal. Owing a gel coat 5th wheel, I know what it takes to keep it up like new. The cleaning products are different, the cleaning processing it close to paint, but with slight differences. Again, here's where the real question of what condition is the rig in the most important. If heavy oxidation, your in for a long 2 days, if light, then you could get by with a one day effort.
I hope this helps a little. Cleaned a lot of this puppies and know about just what it takes.
For your info. here in Tucson area, the local company's and local detailer's charge:
34 foot 5th wheel (light oxidation) $540!! ($16 a foot)
40 foot motorhome (light oxidation) includes roof cleaning (fiberglass)
$640
Hope this give's you some Idea what you getting into. Remember, you cleaning the surface of a small house!!!!