Running Power to Truck Bed

I've got a Leer cap installed, and I don't like the way they installed the power to the cap dome light running off the tail lamp, which requires me to turn on the lights before I can turn on the dome.

I was thinking of running a line from the dome light to a constant power source to avoid this problem.

Any suggestions on the best source and routing to use?

thanks, Jack

First question is... do you have a trailer brake. If you do then there will be power at the back of the plug. If not then you will have to run a constant 12v source from the battery( or the battery junction) along the factory wiring harness. It runs the length of the truck frame. JUST MAKE SURE THAT YOU FUSE THE WIRE NO MORE THAN 6-10 INCHES FROM THE POWER SOURCE!!!! I can't stress this enough.

First question is... do you have a trailer brake. If you do then there will be power at the back of the plug. If not then you will have to run a constant 12v source from the battery( or the battery junction) along the factory wiring harness. It runs the length of the truck frame. JUST MAKE SURE THAT YOU FUSE THE WIRE NO MORE THAN 6-10 INCHES FROM THE POWER SOURCE!!!! I can't stress this enough.

It's an 04 Z71. It has the plug for a trailer, but I dunno if this includes a brake?