You ought to have a nice 50-cal blunderbuss on-hand loaded with salt the next time someone is under your stand. Then again it may be a while before the weather washes out the poop-stain on the tree which may not lead to good hunting. Hammering out the dent from his head hitting the tree stand in surprise may take a bit of effort too.
The favorite thing of hunters around me is to put their stands right on my property edge. I don't mind all that much since I don't hunt and I want those pesky deer numbers cut down, but that smacks of rude.
Speaking of which, the blunderbuss tactic is one my old boss used to use on trespassers. His property backed up to a park, and his land was posted and fenced. People would jump the fence to have a look around. If he was out hunting he left a lasting impression on them. I know... he did it to me when I was stopping over to say hello in a case of mistaken identity. I've never been quite the same when I hear a flint drop.