Mine is mounted under the radio in the dash. I have a telephone wire to the opening by my feet where I can plug in the hand held portion of the unit when I need it.
I did not want to mount anything. Brake controllers are not the nicest things to look at.
I did the same as Tom I used a weather pack connector and some velcro so I can remove the controller when not in use. Despote what some may think, velcro holds it up there very securely I usually have to give a firm tug to get it off.