RE: Stands per Acre
There is a big difference between the number of hunters on a property and the number of stands. I think 5 or 6 hunters on 80 acres is too many. I don't think you can have too many stands on a property. I have 9 stand locations on my 42 acres. Two of those locations have both a tree stand and a ground blind. I also have 4 more locations in mind for stands in the future.
Different locations are for different times of the season, different wind directions, etc. Some locations may not even get hunted some years if the situation isn't right for that stand on a day when I am able to hunt.
Usually I am the only hunter on my place. Occasionally my dad or brother may hunt a day or two. Except for them, I do not have anyone else hunting my property.
In your situation I would be more concerned with the number of hunters on the property, than I would be with some of them wanting to add more stands.