Youll get a lot of conflicting advice here..
IMO the renogy did not get good reviews when I was looking for a controller...
And also my opinion is to use 24 volt panels right from the start..
Like two 270 watt panels hooked up in series.. Its my opinion also get the voltage to the controller. Dont worry about the shading of panels gurus. They are on the roof of RV. shading is a mute point. Either youll have shade or you will not. There is no inbetween really.
Now you have 540 watts and 80 volts to the controller..
https://www.renogy.com/renogy-270-watt-24-volt-polycrystalline-solar-panel/Thats say $525 for two panels.
Couple it with an epever tracer 40 amp @ $190. ( They went up in price since I bought it a few months ago.
https://www.amazon.com/EPEVER-Controller-Display-Battery-Charging/dp/B01GMUPGZA/ref=lp_11751779011_1_1?srs=11751779011&ie=UTF8&qid=1518804803&sr=8-1&th=1Now you are up to $715 bucks..
Just get proper wiring and install and your done..