I've got to say that sounds like a major pain in the butt. I can run my forced air furnace all night in 20deg weather and still show full green on my batteries. (33' 5th wheel) That was before I upgraded to 2 6volt batteries that last much longer than the 12volt deep cycles that I had before. With a 50 watt or better solar panel you should be able to re-charge them during the day.