Funny story (maybe).
I stopped by the shop of my alarm guy to see if he had any of the battery terminals that allow multiple connections to the battery.
We were talking about running a wire underneath the van along the frame and popping it back up through the floorboard in the rear of the van.
He told me to pop the hood to see what setup I had so he could make a good recommendation. We looked at the terminal and noticed two large, red cables (0 gauge and 4 gauge). already connected, one was the battery cable, the other was unknown.
He asked my where the 2nd cable went and I didn't know but I did remember seeing a similar red cable under my passenger swivel seat that had been terminated.
Long story short, the cable was already in place. We hooked up the inverter in 20 minutes and I now have 1000W of power in the interior of my van.