When I did mine I just ran the wiring on the outside of the truck. You can run it through some of the plastic all weather plus heat resistant conduit you find at any auto store in the wiring section. Feed the wire in the conduit first seal up the ends with an all weather paste and if you look under the truck on the driver side there is already a conduit line that runs tucked up along the frame all the way up to the engine bay. I zip tied mine to that all the way up. Then drill through the engine compartment right next to the hood release cable. Feed the wire through then seal it up with the rubber paste. I will get a link on the paste stuff, its from the same company that makes plastidip. Then run your wire to your head unit. Everything is tucked up and away and looks really good. I did it that way so I wasn't tearing panels out in my truck to run wire.
Maybe another idea to save some pita...
