I'm really confused why people are so hanged on rope [solution; pun intended]. I have stainless steel O ring over aluminum rod, which is 10mm in diameter, essentially the aluminum version of
https://321kiteboarding.com/collections ... rowave-rod
After a session with one unintentional, gone violent kite loop I noticed slight wear dents. With such experience I'd expect you would have to replace rope every 10 sessions or so. Also, keep in mind that your nylon rope may be rated 1000 lbs, but at this angle the kite pull is levered and augmented perhaps as much as 10x.
Therefore, why metallic rods are so unpopular? Friction is something very easy to add, for instance alum against steel slides not as eagerly as steel vs steel. Also a rubber cord can be added to keep the O ring centered. The bonus for solving this little problem is that you have some sturdy attachment point, which don't have even slightest tendency to loosen up.