Two independent Alternators.
This is what I use to connect the Camper and the Trailer, It is separate from my other connector. I cut the cable in half. One end connected to a permanent cable clamp on the trailer RV battery, the other connected to RV battery in the camper. The jumper cable scissor clamps are not used.
I also used similar size wire to connect the two RV batteries under the hood to the other two..
The vehicle battery is in the stock position. I had to move the radiator overflow and build a bracket there to hold the 2 RV batteries there. I have a one hundred Amp fuse between the two under the hood and the two other RV batteries.
I did this mainly because the battery isolators I found greatly reduced the amp flow to the RV batteries in favor of the Chassis battery. The chassis requires a lot of amps with air conditioner etc, running.
Cables