Take the proper personal defense courses and KNOW THE LAWS. Have you thought about putting up some trail cams with IR flash to see who is coming and going? You don't have to spend tens of thousands, but a video surveillance/DVR system that can also be viewed over the internet may be a wise investment. If you have an encounter with a trespasser or thief, it is likely you will need an attorney. Try to prevent any direct encounters and look at investing in appropriate surveillance equipment that can give law enforcement the information needed for investigation.