Since I wanted to have a current meter on the control panel the first step wast to go through all the wiring in the “One Stop Service Center”.
With a little effort I got all the trailer DC grounds connected through a big metal wire nut. Since I didn’t have a proper ground distribution bar, and this was all ready in the trailer, I re-stripped all wires to get nice shiny copper and made a many to one connection through the bolt. I lightly coated everything with Vaseline to keep it from oxidizing and then wrapped in an inner tube to keep it insulated from everything else. At the same time I put in a switch to disconnect the battery and finally added an old current shunt resistor from my parts box.