It looks to me like you know your way around a milling machine. How about using Delrin instead of aluminum.

My idea was to machine a block with two parallel 3/8" dia. holes. One will clamp to the cable guard like yours and the other hole would clamp onto a very short rod with an EDS stopper on the end.

It's killing me, the job that I have now only has one of those POS Enco mill/lathe. I wish that I had a bridgeport or better yet a Mazak in my garage.

Check out the picture of the QD and Stabilizer that I machined on the enco.