My recollection on my 87 before I changed out the panel was that on the AC side, it had 2 fuses, one was used for the battery charger and one for the water heater. The cabin receptacles were protected by the main 30 amp fuse. Although not an electrician, in a home situation, a 30 amp circuit would require 10 ga. wire and Im not sure what ga wire runs throughout the cabin. This is one of the reasons I changed out the panel so I could have a separate circuit for the cabin as well as add a spare circuit for future air conditioning.