You haven't ruled out tri-pod or quad pods have you? They sell them in 14' + configurations and don't need to be any where near a tree. A good way to use one in the woods is to erect it within a limby tree or directly behind the tree you would normally hunt from.
I have a 10' & 14' model and have had many shot opertunities at spooky east Texas deer from both of them.
Ground blinds are a great option, but don't rule out free standing bow stands- ala tripod.