i also ran mine down the pillar and through the fender to get it to the battery.

using a relay and trigger wire is the best way to eliminate large wires that run into the cab, i ran 2 powers and a ground into the cab since i have a small LED light inside my switch for when i have it on at night. i just mounted my switch down by the parking brake release handle, didnt want to drill into anything or screw into anything so i just used the screw that goes with the mounting plate for the release.

steve