[tsubaki]

bigshrimpin, do keep in mind, this guy is in a business situation. The less contact the better.
If it becomes too much of a problem to do business where he is, he will move. Unfortunately this will take time.
Constant visual police activity, even undercover (they know what their auto's look like) will keep the "less than desirable's" at bay.
A clean environment and good lighting, usually is a big turn off to these guys.
Only one problem, they usually start cranking up around 10pm to midnight and get going real good about 2am.
Generally just having your presence known is about the best advertisement there is to reduce any suspicious activities.
I do like the "baiting the cops" approach though!