I sure do enjoy your "Cat Ladders Hall of Fame"! Attached are some photos of our cat bridge - that goes from a large pine tree to our 2nd-story condo window (about 12 feet away). We built this since our condo door opens into a common area that has another outside door at the bottom of a staircase. We have 2 black cats, and the younger (long-haired) one Gus has learned to use the bridge and the steps on the tree. We have a cat door in the window. (It would be great if you want to include our bridge/steps on your site. We got inspiration from your photos in the first place.)
Martha. Durango, Colorado.