Wellis77,
I did some more thinking and research. My plan to set the system up is with one power cell in the engine compartment, the master cell inside the car, and an additional powercell in the trunk. Looks like I cannot eliminate as much of the interior wiring as I would of liked. To minimize it and for max safety the high power stuff will be short leads so I want the power cell close to the headlights. That means I have to run wires back to the dash for the indicator lights or run them from the trunk mount cell.
I was hoping to just have the communication wire go through the firewall. It still might be possible if I can run everything else from the trunk cell.
Does this make sense?

Jon