I do agree that there is a line that can be crossed that means you have gone too far. However, when all other options have been exhausted, what are you to do but defend your property. I don't like to think of people getting hurt by running over spike traps, but the simple point is, if they hadn't been tresspassing, they wouldn't get hurt.
...that line can b a little gray....how long and how much do you take... how much damage will you let be caused and how much money to be lost before you take actions into you own hands...
That is one reason I said to make sure you call the supervisors of the Game Wardens if they are being no help. If you document who you talked to, when, why, etc that can be used when you go to court (if it gets taken that far by someone). You can easily plead the case and show the proof that you had done all you could legally and nothing was being done.
You could still end up in some hot water but it all depends on what type of person you are as to how far you want to take things.