Hi Smoothrun.

I'm no auto electrician but I can do a reasonable job if I try so I made up a distribution box that is fully fused for most of my extra add-ons and they are many.
I used some heavy cable directly from the second battery on the passengers side and drilled a hole in the firewall just above the passenger foot rest but close to the transmission hump for an easier cable run. I installed a water proof grommet and ran the cable through (2 of each + & -) one goes to the Fridge with Anderson plug and the other to the fused distribution panel. I made a hinged fold down shelf behind the front 2 seats for the remote head radios and distribution box to sit on, its mounted to the cargo barrier and it's up close to the ceiling out of the way. So all other accessories are into the dist-panel, 4 radios, internal LED lights, inverter etc. I can do photos if you want.
Cheers