Honda Pilot dinghy

We have been towing an 05 Pilot for a year, using a set of magnetic lights on the roof. The loose wires are scuffing the paint, and I'm ready to wire the rear lights with a set of diodes. Has anyone done this who can offer advice on where to run the 4-conductor wiring? I have a Pilot shop manual, so can find directions for most things. I am considering running through the firewall, and under the carpet to the rear side trim panels. Any thoughts from someone who has done this?
Thanks for your help.