So at home on shore power you want to float at 80% SOC? So you have to disable the charger and solar, get the 120v in from shore power and your 12v from battery for if you want to do anything out there in the RV
If you get them down to 80 and disconnect then your inverter/charger is dead plus no 12v. With the marine shore connection, can you by-pass the dead inverter with the shore power cable and use your spare converter for 12v?
On the way home from camping where the batts are above 80, you can kill the #4 pin supply from the truck (Chev, pull Stud 1) and no solar, and as suggested run the fridge on 120.