Be careful how tall you make them. I have hunted in a buddies blind that is super tall and overlooks an area of lower elevation. It is actually hard to shoot at anything inside of 100 yards because of the angle.
True, I have an 18' tower that was great in south Tx but way too tall in northeast Tx to see under the trees. I cut the tower in half to make 2 towers and works much better!
For years we hunted in 10 foot towers in the hillcountry, thought it was the only way to go being off the ground. Finally sat a ground blind on the place and it was night and day different, the place had a brows line that allowed you to see a long way when in a tower stand you wouldn't be able to see any of it.