Not sure what the difference in design or aluminum extrusion profile looks like on the Motor Guide compared to a MinnKota but maybe you could drill a hole through and add a pad lock? I know my quick release bracket on my MinnKota allows for a decent sized lock on there to prevent the release lever from unlocking the motor from base.
Some of the older ones can also use a through pin lock as well .... maybe something can be adapted for the Motor Guide?
https://smartlocksguide.com/best-loc...rolling-motor/