I like your idea of being able to tow AT guns.
You are desperately trying to back your AT gun up from the incoming blob of infantry, but you don't make it and they abandon the AT gun. Que the M20 coming in to save the day and drag the AT gun back to safety.
Too bad they will never add this.
That actually sounds like a pretty bad idea for now 'cause then an M20 rush which took out an AT gun will be stealing it easily too!