My father in law had about 8 acres we inherited after he passed. He had owned it for decades, never used it for anything other than camping. We went out there a few times before selling the land, and I remember a tree like that. My wife has some photos of her dad and uncles sitting up in it. The horizontal part was about 6 ft off the ground.
I ran across the link you posted a few years after selling the land. Wish I'd known the significance before. Thanks for the reminder!