I think that would be a great place to store the bike for the winter. That's probably that guys "dog house" to get away from it all!!
I built one a little smaller then that in my younger days (I think the floor is still up there) and I had a wood stove to heat it so I could spend the winter days up there!
My neighbor who is a shrink built a tree house for his two daughters that wasn't quite that extensive but was close. For two weeks I listened to him cussing while he was building it since it was about 40 feet from my office window.
When he moved into the house he did a lot of ground scaping and had undercut the soil on several trees, one near the tree house. About two weeks after he built it we had about a week of rain and one of the bigger trees fell over and smashed the tree house along with my fence and phone lines....g
You know, for a mental health professional I thought we were going to have to dart the guy when he saw that smashed tree house.... :shock: