Ideas to combat trespassing on a commercial restaurant

[Andrea Finkelstein]

Hi. We own a restaurant building in Downtown Phoenix, and my tenant is having a horrible time with indigence hanging out or parking there at night and leaving dirty diapers and other items. We have all the no trespassing signs. Has anybody found an effective way to combat this? They have very few parking spaces and their patrons are leaving due to inadequate parking or the horrid way it looks when they arrive in the morning and clean up takes far too many hours each day. Any suggestions if someone has gone through this or I would welcome any ideas. Thank you in advance.