I am also considering buying the Renogy 100W portable kit. I am planning a trip this spring to Arizona and Utah, so this is a good time to try out solar. But I live in Michigan and mostly camp in the woods, so I am not ready to go all-in for solar. I don't want to put holes in my roof for just this trip.
Two 50 W panels is more expensive than one 100W, but, as DAS26miles mentioned, it is a lot easier to carry if you aren't going to mount it permanently.
My goal is only to reduce generator run time. 100W of panels certainly won't eliminate it. I figure that the only times I will get a full charge on the battery is if I run the generator in the morning until the current starts to taper, then let the solar finish it off. Good to do every few days, but I won't do it every day.
My batteries will be a pair of GC2s. We have a small TT and seem to use about 40-50 amp hours per day, as long as we don't need to run the furnace a lot.
The ViewStar controller that comes with the kit looks good since it has settings for charge and float voltage, but it has little room for expansion. The 15 ft of #15 wire between the controller and the battery is obviously a problem, so if I decide to drill holes, the first move is to put the controller closer to the battery.
I'd be interested in any other comments about this kind of setup.