Here is the BB sitting on O54 track.
I was able to push it back and forth on it and it took it. The tender on the other hand felt like it would climb out. If it had any blind wheels, it might of made it fine. As for the close coupling, I don't know if it'd of taken it. I don't have anything in between O72 and O54. It would not go on O48 so I didn't even try placing it on O36.