SN6400 Wiring for Towing a Trailer or Pup

[cd6400]

Folks,
Looking for some advice...specially from those of you that have installed or are towing a trailer that uses electric brakes. I have a 2011 SN6400 that I would like to tow a car trailer or flat tow a pup. What I discovered is that GS did not carry the RV brake signal wire or the 12V hot wire to the 7 pin hitch connector. What is there on mine is the standard brake light, turn signal and running lights. I intend to use/install a standard brake controller (Prodigy brand) but have not seen the ability to pick off the brake light signal wire typical to this brake controller installation, nor is the coach pre-wired to make this installation simple. How did you install your brake controller and how/where did you pick off the brake signal and the 12v to trickle charge a trailer battery that is possible via the 7 pin connector? GS makes a big selling point about the towing capacity of this rig...just can't believe they didn't "finish the job" by pre-wiring the coach to the hook up.