Nice job Charlie,

I have a similar setup on the back of my bike but I use a small ball joint...



I changed this setup when I motorized my trailer as I didn't think the towball would hold up, plus I needed the trailer to be able to Yaw n' pitch - tip on bumpy ground. But I ended up going back to the ball hitch, it has held up nicely but I dont have a lot of yaw n' pitch.

Looks like you have solved the Yaw n' Pitch with the first joint on your hitch - if this in fact swivels?



Regards
Tom