A word of advice from a guy who used ladders to make a living, 30 plus years.
Place your extension ladder against the RV (wrap a rag, t-shirt, etc. around the ladder to protect your surface) with at least 3 feet extending beyond the step on/off point. Walk up, holding on to ladder, step off. Coming down, hold the ladder against the RV, step on the ladder, walk down.
If you step on a step ladder from the roof you are asking for a fall. It is like the boat and the dock scenario, as it goes away you fall off the roof! If you must use the step ladder, do so with it folded and leaning against the RV.
BTW, at 6'4" and 230 lbs, my size 14 boots have walked/worked all over my roof with no apparent damage to anything.
2001 Ford F-350 Super Duty CC Dually, 7.3 Diesel
2013 832IKBS Flagstaff Classic Ultra Lite, Hensley Arrow Hitch, Carlisle tires
2016 days camped....211, it ain't over yet!
On the road to ALASKA May 6, home Sept. 13, 2016. 23 states, 3 Canadian Provinces, up to the Arctic Circle, 17,300 miles, 131 days on the road. 1 flat tire, 4 oil changes. What a beautiful trip!