You can sheer the sheer pin when pushing, but you may not notice until the prime mover stops and the A/C continues
Not taking the piss but has nobody thought of putting a dead rope steel cable between the front and aft connectors?
You could even be fancy and run a hydraulic sensor up the middle of it and when it pulls tight when the pin sheers it will ring a bell. If you put the cable over a pully it will sound the alarm when it breaks pushing and pulling.
Or would that just spoil the fun?