Servo Operated DPDT Toggle Switch for Motor Reversing
If your speed control has no reverse feature, you can reverse motor battery polarity with a heavy duty double pole double throw toggle switch actuated by a servo with a pushrod though a hole in the handle using a servo saver
( two wheel collars and two springs with the toggle handle in the middle). The spring makes servo throw non-critical and prevents binding.The attached diagram shows how to wire the switch terminals, and input output wiring
Use a heavy duty truck type dpdt toggle switch with plastic handle rated for 10 amps and a standard servo.