The batteries can be charged in just a couple hours, true, under good conditions. Often we are camping in the forest so our cumulative charge may take over 6 or 10 hours to achieve fighting shade and such. When under perfect conditions, we leave the fantastic vent running to keep the camper cool throughout the day, charging computers and phones etc or running other items. I would say to go for the higher power 140 + 140 watt panel setup. You can also setup a secondary load like charge your truck battery when the TC is full. A while back, somebody on the forum had a water heater element specially made for just such a purpose. I think it was dual 120AC and 12DC as a diversion load to heat the water. Perhaps not hot but warm. I think there is more reason to have a larger solar system than not to.