I would try and talk to him about the details of hunting. I think some farmers have no idea why you would want to build something in a tree on their land. Try to educate them on the logic of it and how important it is to hunting. Let them know that it' s not just building a tree house so you and your buddies can hang out. I' ve found that some of the landowners simply have no clue and if you discuss the fine points with them they may understand.