Restarting after a year+ absence (various reasons, not for publication here).
In reviewing online support forums, I see another recommendation. I’m using the SkyShed pier, and the supplied pier-to-adapter plate connectors, which is 4 long bolts the mount sits on, that enable leveling.
It’s pointed out that those are a (rather obvious) possible source of flexure. And they’re not really necessary – assuming the pier is reasonably level, proper polar alignment in the mount will overcome any fine-tuning of leveling.
So, new first step, that I’ll do on the first opportunity: Remove those leveling bolts and mount the pier plate directly on the pier. The only issue will be that the space between the pier and the plate has been a useful “cubby hole” for various cables, and those will have to be relocated.