Dimming won't help since it's only dim while idle. It goes to full brightness during an alert.
It's easy enough to test it since I have a PL3. I can park my car, leave the lights on, walk 100' away and shoot, and see if I can see the LED.
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If you have other electronic devices on the dash (dashcams, gps, etc) they also would be a plausible (to the point of being a more likely) explanation/reason for the LEO if he even noticed light on the dash. My radio (in dash) I have set to blue, and that sometimes reflects at night into rear glass, and then (more faintly) back to front windscreen.