Thats what I have planned for the other switches as well, LED rock lights, and aux reverse lights. I've heard of a couple other ways to get wires into the cab from the roof. I've see guys run their wires along the rail, and then thru the third brake light, and into the cab from there.
I've also heard of using one of the holes that the OEM roof rack rails mount thru as a port of entry. You're limited on size, they're a pain in the ass to get to, and you loose one mounting screw for the rails making them weaker. Another option would be to do something similar, and go under the rail. Un-mount one of the roof rack rails, drill a hole in the bottom of it, and a drill a hole in the body in the same exact spot. feed your wires thru the holes, thru the rail, and up to your lights. Seal it from the inside, and you're good to go. (there's only so many ways to do this...) Good luck!
