How polished are you at handling rejection and maintaining your confidence and optimism in your pitch to clients despite it?

Police won't help in most of these cases because it is considered a civil matter.   

Yesterday, I got a default judgment on a 2-count eviction (for nonpayment AND for a confrontation with the property manager involving the police).

You may not like all the taxes you pay, but you probably like the roads you drive on, the firefighters who put out your house when it catches on fire, police, schools, airports, football stadiums, regulations against poisons in toothpaste, and numerous, numerous other things the government does.Track down and work with a good accountant or tax strategist.

The longer answer is you may end up having to "police" them to make sure they are not using the other acres which may not be feasible.

Hopefully this incentivizes the tenant to police his friend better.  

When I asked him to move it, he said the police had visited and that he would move his car in a few minutes.

Install cameras to catch any dumping activities and then report to police who should issue fines, make arrests, etc.

Called the police once we got a download on a memory stick we gave them.

The police should be able to help you with this if you don't have an emergency contact number.