George,
I did the same project in March. No doubt, it's a handful of a job. It's not especially difficult but it does take some planning and time. I'm glad I did it because it forced me to learn a good deal about the truck and that knowledge has come in handy many times since.
I'd recommend you first read everything you can here on the forum. Search for "Gobi PIAA". Here's my
S.O.S. thread on the install.
Ken is correct about going through the marker light and not needing to drill holes. Suggest you get on a ladder and remove the driver side, front marker light and you'll see a rubber gizmo/boot. You'll need to pierce that to string your roof wires through.
I'd also recommend you tackle the project in two phases. One is assembling the rack and building its wiring harness. The other is wiring the truck. Install a waterproof quick-disconnect near the marker light and on the rack then mount the rack, plug it in and you're done.
Rod