It great that you're approaching this in a civilized manner and not coming at with hostility. Who knows, maybe you'll end up with a life long hunting buddy.
Now the downside is he's only perhaps 30 feet onto your Dad's property. If your budding relationship with him goes south, all he has to do is move the stand 10 yards and he's still hunting the same area and there's not much you can do about that. 12 acres isn't much land when considering the home range of deer, so if he's not on your father's property killing deer, he's gonna be on the adjacent property killing the same deer.
I think your best bet would be if you, the renter, and the adjacent landowner can all come to an agreement that both of you can hunt each other's property.