Then one day, months later, I got a text from a camera assistant friend. Apparently my new improvement had been named... the Zwivel. And they made a video about it. Check out my comments below the video on Vimeo for more information about that story.
After a year of working with it, I've made another little improvement.

I call it the "Zlide".
It's the part that says "Zacuto USA" plus the rod to the upper left. It's basically a Minimount.
The difference is a set screw on one end to allow clearance from the camera body.
It allows you to move the entire assembly front to back without interference from any mounting brackets or other things you may have attached to your rod on the top mount. In this case the rod is 15mm but I'll bet there is a way to make this happen for 19mm as well.
The Zlide is also pretty handy because it allows you to adjust how close to the camera the vertical rod is. Sometimes you need a bit more clearance than you can get without it.
Another feature is that it allows placing the whole thing farther forward or back.
So just call up Zacuto and order your Zlide. Well, maybe you should call it a Minimount with a rod for now.