First make sure no other loads are on the circuit you are plugging into at the house. A 15 amp circuit is plenty to run the refrigerator and your inverter/charger to maintain your batteries, so don't turn off battery isolation switches. Not sure what you mean by aux power switch. While on shore power, you can run the refrigerator and your converter/charger to maintain house and chassis batteries. In addition, you could power a fan or two but not the air conditioning.
You might enjoy reading this to learn about your 12 v and 120 v systems:
The 12volt Side of Life (Part 1)