RE: To Close???
If you are in a good area with plenty of cover and camo, I would say 5 yards or 15 feet off to the side of the main trail will be good enough. If the leaves start falling and you lose that good concealment, then you would want to move further off the trail and perhaps get some more trees between you and the trail.
I have one stand location I use from early September to early November where the deer might come directly under my tree or from 15 yards to my left or right. They are approaching a feeding area and sometime wander a little bit when getting close so sometimes they are right under me or just off a few yards to either side. I'm up about 12 feet off the ground and concealed quite well with branches and leaves all around me. Last year I had a 6 pointer almost bump right into the base of my tree and he never knew I was above him. I think you just have to have good concealment and be still.