I guess it mainly depends on your budget, and what will fit. Weight is also a big concern too.
200 AH is what I would consider the minimum for a RV. IF you have solar, then you do not need to store as much power, as you are making a lot each day.
Think of it like a water tank. If you must withdraw 35 gallons per day, and need to stay for say 5 days, then you know how much you must start with. But if the solar is putting back 50 AH daily, then storing more than about 200 AH is not required in your case, as you will gain 50 AH daily.
Your RV will consume about 35 AH daily just to run the CO meter, propane leak detector and refrigerator.
The water pump is insignificant load, as it will pump 2 GPM drawing 7 amps per hour, or empty a 120 gallon tank with only about 7 amp hours.
Have fun camping!
Fred.