Glad you liked it, Cowpoke. I was a public defender, and had to represent some of the rural Yahoos who did these kinds of things. I used the time to find out how they thought, and what motivated them to do acts of vandalism. Basically, they are selfish people, who resent outsiders. If they have been playing, and hunting, legal or otherwise on some property since they were little kids they deeply resent being told they are no longer allowed on the property.
New owners have to learn the lay of the land, and that includes the history of who has used their property and for what purpose. You can gain that history from a local guy. But, he will not tell you unless there is something in it for him, too.
Most of the times, if you reserve that leased property for your own family hunt on opening day, and then let others have access the rest of the season, or on any other schedule, they will work with you, and not against you. They do understand that you are paying money for that lease, or to own the property, and like anyone else, you want value for your money. If your manager is worth anything, he will enlist the locals who want to use the property to do a Spring Clean up day where they help pick up trash, fix fences, help plant trees and shrubs, or fix locations for feeder stations, or food plots, help plow, and plant,these food plots, and in general help improve the carrying capacity of the land so there is more game for both the owner and them to hunt. They in turn will gain an education in wildlife management techniques, which they can use on their families properties, and approach other neighbors to do on their properties. so that there is more hunting for everyone. It just takes direction, and you can turn vandals into good neighbors, again.