Recently I completed the design, fabrication and water testing of a modular steer-by-wire add-on for any electric trolling motor.  It simply attaches to the side of the motor mount, without hampering the normal operation of the motor.  The total cost for this option is about $25. The device provides steering via a momentary rocker switch attached to the drive with a wire of adjustable length. It can fit on, and be any distance from, most any trolling motor, and draws little power from the battery.  If interested, go to the Electric Steering tab on the above menu bar.  I would also be interested in receiving feedback regarding this design, as I wish to make it as universal as possible.
               Ken Simpson