Another configuration of motor mount. An issue with the other was that if the threaded rod drifted out of its path, it put stress on the motor. The function of defining the path for the threaded rod needed to be separated from the motor mount. Hence, the second angle iron 8" below the first. Nice thing about using angle iron is you know the holes are aligned relative to the center rod. You can also see another 1/2 cinder block which I added because the first angle iron was a bit whippy from being cantilevered out so far.
The eyelet nicely prevents the t-rod from turning, but one of the purposes of the in-line ball joint was to handle the angle change (and associated length change) when the mirror is at larger angles. The fix is hardware that pivots in only one axis, like this, but I can't find it cheaply. They're about $3 each in large quantities, but that's still pretty pricy. Working on it.