Wiring brake controller to a 2003

[kjonus]

I'm trying to wiring in trailer brakes to my 2003 however for the life of me I can't access the wires to the brake switch. I'm wondering if anyone has any tips or options. I'm thinking of just running another wire from the back of the suv which is tapped into the brake light itself, but I'm wondering if this would not be a great idea.

Thanks in advance
Kent