Hi George,
Not having a yoke to build a plug out of, I have let this project wait. Just a few days ago I realized that I had such a yoke permanently attached to a 2″ box steel pole on an old competition cart. I took that off and it fits well into the aluminum which fits well into the steel frame for the arch. I may be in business with it this weekend, just need to cut down the aluminum tube which I didn’t want to do on a whim.