I'm now at one third of the level. Everything is coming along nicely, and the tree problem has been solved too, though the solution itself isn't 100% glitchproof.
I've still got some trouble with the foreground and background layers, but that'll have to wait for now.
Everything is tested and Lori is able to get about too. I'm quite content with the looks. I can upload a few screens, as long as somebody is interested.