The basic idea is there's two major ways for using your 12 volt power. One is to increase the capacity such going from 74-100amp hour to 150 amp hour plus.
The other (my preference) is to reduce the consumption to the point where the 74 amp hour
battery is plenty. I've done this by all LED
lighting,
solar battery charging, and frugal use of the
furnace. The only things that draw from the
battery are
lights, charging some electronics and the
furnace. No electric water pump, no inverter running 120 appliances. A 65 Watt portable
solar panel.
I can go as long a I want without worry.