To really do the tension right, I suspect you need a spring to compress the cut end of the nut. With a static adjuster (like a NPT bushing) you are depending on the flex of the nut to ride out the inevitable irregular parts of the shaft. The better the spring does it's job, the less wear on the nut. Coming up with a wrap around spring that has the right spring constant could be a bit interesting ....
Maybe some sort of hose clamp over rubber foam trick ....
Maybe some sort of hose clamp over rubber foam trick ....