We have a 230 amp hour AGM battery bank in our RV. When camped for any length of time (3-4 days for us), we recharge with a 650 watt Honda generator feeding the RV's stock Parallax 45 amp (Model 7345) converter. This takes 5-6 hours to get the batteries down to absorbing only around 5 amps (which is not a full charge state) using this generator feeding the converter. The generator's 0.5 gal fuel tank will run it for 5-6 hours. When camping, we recharge whenever battery terminal voltage drops down to 12.0 - 12.1 volts.
The rare times we camp longer than 3-4 days, we supplement the 5-6 hour charging times on the little Honda with periodic idling of the main engine for up to an hour to help with occasional recharging of the batteries closer to a fully charged condition. During travel between camp sites, the engine alternator brings the AGM batteries up to full charge within 3-4 hours on the road. I call the batteries as about fully charged whenever the current flow into them from the alternator drops to less than 0.5 amps.
The above procedures work good enough for our camping style due to the faster recharging rate of AGM batteries at whatever voltage being applied (due to their low internal resistance) and due to us traveling at least as often as every 3-4 days. We don't hit our battery bank with large drains such as running a hair dryer or a microwave via a large inverter ... and our lights are all LED, so this helps extend battery life when camping (we use the built-in generator for the A/C, the hair dryer, and the microwave). Adding solar would be a good option to improve camping flexibility, but not having solar has little impact on our particular camping style. IMHO, a self-contained RV should start with good generator capability so hot weather is not a restriction ... with solar added later for more flexibility to extend camping time in one place.
So ... I guess the bottom line is that only a 650 watt generator can be adequate under certain RV'ing conditions using specific combinations of RV equipment.
