That is our preferred method of RVing, at the minimum a pair of 6 volt golfcart batteries is truly advantageous, purchased our current pair from Samsclub and they are less expensive than most car batteries. At this point your 12 volt battery has already begun it's final descent into uselessness since draining to such low capacity translates to early and imminent failure, not a biggie as we all started out our RVing escapades with a single 12 volt jar from the dealer. Golfcart batteries can take repetitive deep discharges and readily bounce back making them ideal for this type of RVing.
When camping off the power grid best results are achieved using a multi-pronged approach. Once a quality set of batteries have been integrated into your 12 volt distribution system, a converter with proven smart charging technology is critical to the equation. Unfortunately, WFCO doesn't fully go into bulk charging mode where 14.4 Vdc or more are required to get batteries up to around 85-90 percent threshold in a couple of hours of genny runtime. Talk with Randy at BestConverters.com for and easy to swap out upgrade that will make your batteries very happy.
Since you have a Champion 3100 inverter generator it's apparent that you intend to do more RVing off the power grid. We have the remote start version and it has handled every item on our rig with ease, very efficient but not something you want to run just for recharging or watching TV. Adding solar can significantly reduce genny runtime for recharging depleted batteries, about 100 watts per battery will net you full batteries by sundown, sooner if they aren't too depleted. With our inverter we can use our HDTVs, HD Satellite, Bose and Bluray gaming system, among other portable devices.