Please add your location as it might help in getting a bit more exact help.

NAL.

Contact the police again and escalate to someone in a leadership position. Take copies of all video/images you have from your camera(s) with you and save copies both on your computer and in the cloud. As far as I know, all states but one have anti-stalking laws. While the definition of stalking in each state varies to one degree or another, I'd expect showing up in the middle of the night on your property and poking around uninvited would qualify.

Regardless of what the police tell you, I would look into a protection order. For this you would contact either the prosecutor's office or a court. Search "how to file a protection order in X" where X is the name of your state. That should get you the steps you need to follow. If the order is granted and the man violates it by continuing his showing up in the middle of the night, the police would likely act.