It's purely a matter of how much you wish to actually recharge the batteries.
Maintaining an already filled bank then a small wire charge lead line will zero out refrigerator loads.
Back in Fred Flinstone, days, I discovered much to my chagrin twin
six awg wires charged a 12.1 volt trailer battery bank at a whopping thirteen amps from a 14.4 volt alternator source. 500 amp hydraulic ramp big rig plugs and sockets were used.
The futility of this left an impression lasting five decades.
I switched to 2/0 cables and got a 50+ amp recharge rate.
Have you priced two aught cable lately? It's also a mother-bear to umbilical from tow vehicle to trailer.
