What gauge wire from batteries to inverter

opnspaces wrote:
As far as the distance, the horizontal run is not that far, more like 3 feet if I went straight from the batteries through the front wall of the trailer. But that seems like a leak point so I was picturing going down from the batteries, back to the trailer then up through the floor. Now that I have a better idea how much distance affects wire gauge, voltage drop, and price; I'm going to reconsider the path to see how much I can shorten it.

I wouldn't do that - if the inverter is mounted in the front pass through storage compartment go down through the floor, along the underside of the A-frame, and up to the batteries. In my case that turned out to be 6', meaning 12' of cable for positive & negative, both 4 gauge for my maximum ever load of 70 amps. You sure don't want to go through the trailer's front wall - instead increase the gauge of the cable to whatever may be necessary to meet your load & distance requirements.