My suggestion is that while you are present, a right-click option on tresspassers to teleport them back to their hearthfire. It would only work while both you and he are present, and would increase the trespassers (and your own) travel weariness, allowing you to stop them, but also limiting the abuse of the action. Some people are only taking shortcuts around gigantic forts

Its aggrivating to work hard for hours on a new claim to have a random passer-by wander on and take everything of value, with no way to stop him.
The guy who wondered onto my land had the gall to say 'Hello, Im a theif!' and take everything oout of my log cabin. I tried standing in front of him to block him in the doorway, but my client exited for some reason (not idling, I had been there about 4 seconds)
Besides this, I love the game, I support theivery and its implementation as a hard to achieve skill, and thus its well-earned, but new-starters with no village or approprite skills as backup could easily by off-put entirely from the game by acts they have no way of stopping.
Just a thought.