I'm headed down the same road you are talking about.
One thing I'm in the middle of right now is trying to get 12v Led lights. The LEDs are much more efficient than incandescent or cf lights. Running them on 12v directly from the batteries will save the cost and efficiency of the inverter. The same would apply to what R Scott is talking about with the rv pump.
Check out nickel iron batteries. You pay a serious premium to buy them but they don't need to be replaced like lead batteries. They are almost impossible to damage from missuse.