One thing that can be done is asking the right question, <not legal advice but a suggestion or idea. Always consult a lawyer> Basically If someone comes up to buy their property, asking them to sign a statement that basically states that they are not working for and/or acting as an agent for directly or indirectly for the individuals and organizations listed below. They say yes you send them on their way, they sign it they misrepresented themselves and the land can revert back to the land deed holder without compensation to the buyer. A lawyer can actually arrange it to keep these people and organizations from getting huge swaths of land.
This is just an idea, you can't beat them with resources but you can with the right legal paperwork and the right questions. An organization also needs to be created to protect and fight back against them by accumulating and information to provide it to land owners.