Each battery will store about 1,000 watts if you plan on discharging them to less than 25%. As a practical measure, only discharging them to about 50%, then you will have only about 100 'useful' amp hours, or 1,200 watts total with only 2 batteries. 4 batteries is 2,400 watts. I had 4 batteries, but now only carry 2 - saving weight. I don't do as much dry camping and my 400 watt solar system fills it daily.
I used to use upwards of 120 amp hours each night, and still was able to recharge in the day. My RV uses 35 amp hours daily just to run the CO meter, propane detector and refrigerator. Anything else is lights, pump, and mostly TV set and Satellite receiver.
Good luck,
Fred.