You are pulling with a Suburban so what I do is not an option for you how ever I will describe what I do for the benefit of all.
I use a “20amp Smart Charger around the farm year round and we have a 2000 Yamaha gen/inverter.
I fished an extension cord from the 4 - 6 volt batteries to the fifth wheel hitch. I set the gen on eco in The back of the truck, plugin the charger and clamp to the batteries.
If we use the furnace all night while boon docking on the road the house batteries get charged properly as we cruse down the highway.
A heavy gaged wire from your truck battery to trailer batteries may take out your alternator.
