I forgot to provide an update regarding my earlier endeavors. I received my super-beefy-for-no-reason-at-all DPDT switches. So I soldered up the electronics and now have a working forwards/backwards 1/35th HP DC motor. It already has a flat shaft, so that's nice. For now I will consider the electronics done, as I work on the mechanical aspects of the design.

For the future:

There is a feature in other high end electric spinners which allow a foot-pedal to be connected to act as a quick-stop. I am not entirely 100% sure how to do this circuit. I don't really want the current going to the motor to have to go through the foot-pedal. Connecting a Normally-Closed socket in-between the motor and switch seems like it would work, it doesn't seem like a great idea as the motor is quite powerful, and the foot-pedal will be hand-made. I would rather somehow manipulate the potentiometer on the motor controller when the foot-pedal is plugged in. I don't really know how to do that, but I'll probably wade through documentation and figure it out later. If you have an idea, please leave a comment.