Hi,
A 270 watt panel will be massive. Where do you plan on putting it? Most rv's have a bunch of roof vents and A/C going down the center of it. Along with a assortment of antenna and shower skylight, I had great difficulty planning for my pair of 120 watt solar panels, ended up mounted above the driver's and passenger seats in my motorhome, where you can now hear the wistle from the wind while driving. If you have a trailer, then no problem, but still go up there with cardboard 48" X 88" and see where that panel can fit without the A/C or antenna or something shading it.
My recommendation is to stay below 150 watts per panel.
SunElec.com also has great prices.
Ibought a simple PWM solar controller for $13 to control a pair of older 45 watt panels that I gave to a friend. Then installed about 10 each 24 LED Panels, with 5050 emmitters, it lights up his house very well at night. It only has a simple 26 amp hour battery (I had one good one from a electric wheelchair) but it does the job in the longer hours of summer. I don't know how well it will work next month though, might have to change the timer to run the lights only 6 hours past sunset.
Fred.