The beaches and a few mountain area updrafts is about the only place you can get a sustained 5-7mph wind to run the big blade type turbines....
The only kind I would even think about being mounted on top of a RV would be the Vertical Axis Wind Turbine... I read about one that looked like the heat wind fans on house roofs made for RV's and was looking for it on-line but never come up with it...
Looked something like this unit...
Being a vertical type you would have the generator down inside the RV somewhere driven by a long shaft... They make magnetic type bearings that have almost zero resistance for turning shafts. You can turn a shaft using a couple of these type bearings with your hand and it will turn for days haha...
The blade type turbines are very noisy and a hugh eye sore...
Roy Ken