I installed a strut from the lazarette wall to the front of the motor. The strut bolted to the motor handle with a wing nut so it could be quickly detached [in close quarters, especially going in reverse, we 'steered, by turning the motor]. The other end of the strut was simply clamped to a flange to allow for adjustments.
PS.The wing bolt on the back of the motor is there to adjust friction not clamp the motor in place.