Well, I am doing my own now. I figured out a way around the universal joint strength issue. I made a universal joint out of 3/16" spectra and 4' of poly tube. The spectra is your universal pivot point. The line is run inside of the tube to give it stiffness and form. One end of the line is tied to the middle of the front X-bar. The other is anchored internally 75% up into the pole.

By using tied spectra, instead of rivets, strength is not an issue. Buy anchoring the universal joint deep into the pole, it creates more of a mechanical advantage. The poly tube keeps the joint nice and straight.