Use the ultrasonic sensors to create a limited Sentry mode. It wouldn’t work nearly as nice as the camera based Sentry mode, but could still be useful. As a bonus, it would have minimal power draw.
I have a pre-2016 Model S so I can’t actually get the new “Sentry Mode”. However, thieves don’t have to know that. I would love to have a “fake sentry mode” such that if there is small movement detected by the alarm, or by the parking sensors, then my center screen lights up with a “Sentry Mode Activated – You are being monitored!” screen.