the problem you have is cameras will unlikely stop them doing anything unless your watching them. most will be aware of them so wear hoodies.

You need motion detect to alert you so you can batter fuck out of them.

also be aware that you need to ensure your DVR card on the computer records at the same or better resolution than the camera otherwise you will loose quality.

If its on the drive you can use motion detect on the whole area a bit better and use IR beams on the perimeter that set off an alarm in the house when someone crosses the boundry. off your land its harder as the software motion detect is not perfect.

Sounds like the same scum each time. only takes one scum family to move in and it attracts the scums friends who are also likely to be scum so one family can flood the area with scumbags.