How about putting in 4 poles, one for each corner, sort of like building a house on 4 stilts, which will allow you to raise it up like a tree house, but still be really stable? How do people build over swamps? I cannot see stability with only one pole, but if you want the tree effect, you could still have one of those poles go up all the way above the roof of the hose, and maybe have a zip line down, or stuff to hang from, or whatever.
I'm seeing a 4 sided room with a ladder on one side, a rope with knots (that goes all the way to the roof) on another side each with a doorway, and windows on the opposite two sides?