I haven't bought a controller yet, just "roughing in" the wiring right now.Which controller do you have?
I had my Prodigy unit mounted next to the OBD port under the ashtray area.
I just had this problem on my crown victoria. I removed the plastic cover under the steering column and used nut certs to mount the controller to the metal dash plate. When I am not towing with brakes(99.9...%) I remove the mount and controller and replace the plastic cover. I use a four pin trailer plug so one brake controller can be swapped with different vehicles.would prefer not to drill holes through dash