I was looking around and just noticed this thread. When I lived in Michigan, my very first day hunting in my life, I had a situation like this. I arrived very early, setup my blind and crawled in and waited. Just around daybreak, some other guy wanders in and starts setting up about 20 yards behind me. I didn't think of confronting, so I got up (noisily so he knew I was there and that he was causing me to move) and went to my Plan B location that I had chosen. Not long after being in that location, someone pushed in some does. Unfortunately, I only had a buck tag. In any case, I would suggest having a few spots planned out, get there early, and decide if you want to confront or not, or call a warden if there is a problem.
I did find that most hunters out there seem to be lazy, and didn't want to go too far from the trail. I was able to find space of my own by simply getting farther into the woods off the trail.
Lastly, I put a dot on my map when I saw someone with a setup and where it was. After a while I got an idea of where people were and were not going, and also where I thought the deer might go because of the absence of people, and/or people walking to and from their spots. No idea if that was working for me, but I saw deer and had a good time.
Good luck man.