Thanks for the feedback, AggressorBLUE!
Here's what I think I need to make it work:
Basically, cut the default Obutto center mount from the flight control mount pack so that only an inch or so remains from the vertical tube, and then weld a flat metal piece on top of it, onto which the Mamba + extension can be mounted... done. This would allow me to use the existing Obutto screws and mounting, location, plus it would be the right height for the extended Mamba!
Here's how I envision that piece - needless to say, someone has to make it for me:
Also, it seems as if that metal plate would have to be scooted back some, or maybe be a little longer than pictured, so that the Mamba would come straight up from where the seat and the monitor stand tubes meet, considering the just over 40cm of travel that the Mamba with extension does back/forth/left/right.
Here's my current Ozone setup: