I would recommend #10 wire if it is not included in the kit. Grey direct burial wire from Home Depot will work great, and not be damaged when exposed on your roof.
I wired mine by going down the refrigerator vent cover, and into the closet next to my refrigerator where the controller was installed.
200 watts is good start. Your RV will consume 35 amp hours per day to run just the refrigerator, CO and propane detectors. You will be OK, and make more power than those loads, but not much more. Expect about 50 - 60 amp hours daily. I had a 415 watt solar system, and could collect about 100 - 120 amp hours daily.
If you decide to expand, you can look for another 12 volt 'nominal' panel here.
SunElec.comI made solar mounts with 6" long aluminum angle from Home Depot. It is very good to keep the solar panels about 1" off the roof, so air can carry away the heat that collects below the panels. At 130F, the panels will put out about 10% less power than if they are only 70F on a 32F day.
Good luck,
Fred.