Well, much of that question, or the answer to it, is beyond my expertise. A question on contracts would be better put to a lawyer than myself. As to how, I can only point to the need and, in my experience, the apparent openness of landowners to this kind of thing.
I don't know what specific barriers there are within the bureaucracy or the legislation to doing it. I just know that it's not being done and that it needs to be done.