[sourdough]

First, I am surprised it came with only one battery since you are trying to power a residential fridge along with the rest of the RV.

Personally I don't go anywhere without 2 batteries. I've always done that (except back in my pop up/first trailer experiences) because of situations I encountered along the way. I don't ever plan to dry camp on trips but you never know what might happen.

If you have either a 12vdc or res fridge I think you will be pushing your luck at the very best; dead battery at the worst. If you have a gas/electric fridge run them on gas. I only run group 24s since I never plan to put them to use. You don't say what yours are but if it came from the dealer that way it's probably a 24. I would just get another battery (2 if you've used the existing one much) a box for 2 batteries and wire them in. It's simple, quick and protects you from a "dang, I should have" situation.