[timgco]

Well, I have a couple of ideas for you.

When I wired the lights on my sig. others GOBI rack, I ran the wires up the A Pillars on both sides. There is enough room to the roof line behind the windshield. Once you take off the A Pillar (two screws) you can tuck wires behind there very easily. I did not go through the firewall to run the switches inside the cab though. There is a boot I went through on the side. If you open your DR SD front door, you will see where GM ran the power to your doors. I just popped that boot out and than ran the wires inside and under the dash. You will also have to pop off the fake air cleaner covers. Just pull hard, they pop off with alittle musce. Make surer to pull straight up though. This should work for all your wires. The best parts is, it won't get caught in the door when you open/ close the door and you don't have to drill through your firewall. To run wires to the back is easy also. You can run them just under the sill plates to get to the back. I think the sill plates just have clips in them. I have not pulled them yet though, so I'm not sure how hard they are to get off.
Good luck,
Tim.