Building a Heavy Duty Charging Circuit for Camper--how big?

I used a 150 amp relay, 100amp breaker, 2 or 4 gauge wire, and the 200 amp lift gate plug. Not all of the run is 2 gauge; the camper side is 4 gauge and only 10ft long, the truck side is 2 gauge, but almost 12 feet long.

No 7 way connector can take a wire bigger than 10 gauge, and that is iffy, and that is the choke point. The 7 way design is to charge a break-a-way battery, not the monsters in comparison in a camper.