Is the land empty? Were they doing harm to it? If not, I say let them stay and ask them to pay a fee. Were they making a mess? If so, I'd boot them off too. If not, be neighbourly and less confrontational. Make a deal. Private (unused) property enclosed in barbed wire and a locked gate serves no one and breeds resentment. Is there harm in them pitching a few tents and you allowing them to enjoy what we have here? Maybe put them to work cleaning the area up. I doubt you'll get much resistance if you approach the situation differently and if you do get some flack kicking their asses out of there is fine. Confiscating their homes is not.
Sorry for the rant - just recalling my backpacking days and all the generosity of those I encountered.