I use the Brake Master 9000 by Roadmaster on my 07' Jeep Wrangler. It's an air system with the compressor in the basement of the coach and the brake actuater lever is in the dingy. It has an anchor mount bracket that bolts to the base of the seat and the other end clamps to your brake peddle. They have many brackets that are vehicle specific and most likely have yours as I have seen many HHR's being towed.
The system is a bit pricier and more labor intensive but is easier to get in and out of the dingy than the "all in one" brake systems and doesn't run the dingy's battery down on your travel.
With a slight modification to an airhose I use the on board compressor to fill low tires if need be while I'm on the road. Come's in handy for blowing up anything that needs air.
Roadmaster Inc. - Tow Bars, Braking Systems & RV Accessories
There are several options out there, this is just one that I choose.
I hope this helps,
Brad