Extra Wires Already There
I seem to recall some few mentioning that they have found extra wires/cables in their bus (front to rear) that were provided by the converter for future use.
Marathon comes to mind, but I am not certain.
I can't imagine Liberty not having done it, they seem to think of everything else.
That wire may be overhead above the finish ceiling.
I also think there is a wire/cable chase/duct over head in which the extra wire lies. You may be able to pull through, with the existing wire, those more suitable to your specific use.