Keep tabs on the local law enforcement agencies. While most cops are more or less decent and won't bother you as long as your not driving recklessly, there are a few bad apples who will bother you for whatever reason. Also, remember that you have no rights on the road. You're fair game for any reason. Get ahold of a mobile scanner and hide it behind your dashboard or in a seat.
Scanners are illegal to have in vehicles in some states and much frowned upon in others.
Run a remote speaker to a convenient but hidden spot with a hidden switch to turn it off. This way they can't see anything that looks suspicious, and you can cut out the audio quick if you get stopped. This will give you an indication of law enforcement activity nearby you and allow you to take appropriate action should your plates get checked all of the sudden. Drive at the proper speed. By that I mean not too fast and not too slow.