May I suggest you get an ACDC clamp meter and turn everything off in the rig and start with a warm fridge. Start up the fridge then clamp your positive battery terminal and see what the amp draw is. This will give you a sum of your fridge and phantom loads sot you can figure out how many amp hours you will be drawing when the fridge is on. Multiply by 24 for amp hours per day...and then multiply by how long you will be gone for what you will draw in WORST case with fridge on in hot weather full time.
Your draw for that time should be not more than 1/2 your house bank capacity.
If you have a pair of Group 24's...75 amphours max
If you have a pair of Group 27's...100
If you have Group 31's... 110
If you have a pair of Golf Cart 6V... 120
Obviously a lot will depend on the temps outside and in the coach...but this will give you a worst case...
If you visit the coach...a couple of hours on the genny can get you back to 80% full in most cases.
Hope this helps and here's an example of the clamp meter type I'm talking about. The cheaper ones are usually AC only current measuremet.