You could also just run a single main power wire to the roof (like 6 or 8 gauge), hook it to a bunch of relays (in a waterproof box), and then use cat5 cable to 'trigger' the relays - it's a smaller cable and much easier to route into the cab (mine runs through the edge of teh door frame)...the relays I use have a small trigger current, so no issues w/heat, etc...and you can get watertight network connectors which makes it easy to disconnect the roof rack (one main power connector and a cat 5 connector and it's disconnected). Used this on two different vehicles for years and works well..