While I had the tooling plate off, I cleaned the crud out of the tapped holes and ran a handful of 1/4 inch stainless steel 10-32 setscrews just below the surface:
They’re pretty much invisible, of course, but they’re all present. FWIW, you need a 3/32 inch hex wrench for 10-32 setscrews.
In the event that I gouge the aluminum surface (you can see the odd ding and blind hole) through a setscrew, I’ll regret doing this. Not having to remove the plate to dig swarf out of the last clamping hole after carefully aligning a part seems like a win.