If fiddling with the touch screen while driving is the issue, you can solve that with software lock-outs. The Mazda's touch screen stops responding to touches at faster than 5 MPH, and if necessary you could also lock out option and setting controls entirely while the car is in motion so that even the control knob couldn't be used to fiddle while driving. Moving control out of the already on board computer and control system and onto some external device is just plain over-engineering a worse solution.