OK, when I started to think about this design I wanted to keep it super simple. The picture I had in my head was a sphere. I found a guy who builds something very similar. He hangs these structures from trees and uses them as tree houses. Very cool stuff.
Reading about his process I read that he also started with a floating sphere (in water not forests) so it seemed like a good start for the thinking.
After a few months I found a few more articles about floating hotels and saw designs of escape pods for oil rigs. They were squashed down spheres with a rim that could be used to get in and out of the boat and, I assume, force the weight distribution to the bottom of the boat making it more stable.
These things were made of steel, but I took some design cues and changed my tsunami ball idea into the walnut idea. Voila!