Another thing to consider. Your RV will consume about 35 amp hours just to run the propane, CO meters, and refrigerator each day. That is about what one of my 120 watt solar panels can produce, or what the generator can recharge into the battery bank in about 1 hour.
So save the fuel, and install a pair of solar panels.!! You will be really happy with them once they are up and running - silently.
And my solar system saved the batteries in my RV. After 12 years, I replaced my original battery bank. I was also able to give them to a friend, as they still had a lot of life in them!
Also I consider it this way. The $3000 that I spent on the solar system (back in 94 - 99, when solar was much more expensive than today) I saved by saving $10 a night and dry camping instead of staying in a crowded RV park. Over 300 nights between 94 and 2005. From 2006 - 2008, I spent more than 500 nights dry camping! Paying for the system twice more!
Fred.