I've responded to your case request instead, but for clarity on the forum:
You're right, the girl rotating underneath the chain is going to be your biggest problem.
Mocha requires any object BEHIND the object you're trying to remove to be tracked accurately. This means for her, her legs and body may need to be tracked accurately in order correct clean out the footage.
In other words, not very easy, especially if you have several minutes of footage to work with and she is going to keep contorting her body around the hoop like that.
Since it's a chain, you may be able to get away with a simpler filled wire removal method, but I imagine there would be significant artefacts from that approach regardless.
I wish I could give you better news!