Most of us use this Charge Protocol Card. I use a paper clip clips to the time when your EV can be unplugged and leave it on the dash inside the EV. You are welcome to print it out and use it.
I like waidy's card. It's courtesy that we really want. EV owners are generally nice enough knowing that their cars have the same needs as other EV owners' do, so I believe the situation of overtime-supercharger parking will not be that bad. Leaving a contact number or a card like waidy's should be enough.
As for musking, then the carpark management should have their own rules to remove them from the charging spot.