set remote sharing prefs in terminal
The easiest tool to set these settings programatically is the kickstart script that Apple ships:


  sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -help


Do read the help since, it warns This script can be used to grant very permissive incoming access permissions.  Do not use the -activate and -configure features unless
you know exactly what you're doing.

That being said, you will want to set a variable $ObserveUser for each user that should be shown a menu indication that screen observation is in progress:


  sudo kickstart -configure -access -on -privs -ShowObserve -users $ObserveUser