I actually just attach it to my right leg with a Velcro/stretch band. I like having it at my fingertips so I can apply it manually when the trailer starts to sway. I unplug it and stow it in the rear floor compartment when I am not using it.
My trailer starts to sway above 65MPH at times because of the extra weight/length of carrying a motorcycle on the back.
The problem for 3rd gen is that there are knee airbags below the steering wheel. When they inflate (explosively) the controller could get launched at the driver and do serious damage. I don't know this is the case, but I wouldn't risk it.
Here are the promised photos:
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This is the finished result.
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It is within easy reach for using the manual brake lever.
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Removing the small wood & aluminum trim piece.
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The aluminum bracket I had made.
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The modified bracket with the brake controller mounted, ready for trim replacement. The trim holds the top of the bracket firmly. To remove just pry off the trim and lift off the bracket - then no sign it was there.
This is a Tekonsha P3 controller. Make certain your controller can be mounted up to 45 degrees off horizontal. I used the included sheet metal screws to attach the controller bracket, then cut off the protruding points on the back. Some foam pieces need to be mounted to the lower back of the bracket to provide support.
I have 6 of the brackets for sale - I had extras made to use up the minimum charge from the metal fabricator. They need the edges smoothed and the top cut around the trim connections. $15 each plus shipping. PM me if you want one.