It's beginning to sound like you travel with the refrigerator
on 12 volt DC. If that's the case it's obviously your problem.
The solution is to run rour refrigerator
when traveling, it's much more effecient.
We tow with a Chevy Silverado that boasts the charging level when the "tow" button is pushed and I've increased the wire size in the truck. On our last trip I tried running the refrigerator
on DC just to see if I could. While eating lunch at a rest stop I watched the Casita
battery's voltage with my plug in voltage meter drop from an acceptable level to drastically low.
So I switched to propane
as I have always used.
Yes when traveling some underwater tunnels and gas stations you need to stop and switch to DC but this is no big deal for me.