Well, that didn’t work quite right…
I’d waited for a few days for the silicone to cure, then put the clamps back in their home. When I went to use them, the pads were firmly affixed to the plate. Evidently, the copper-loaded silicone gasket compound takes a few days longer than forever to cure, which is not what I gathered from reading the label.
It may well be that adhesive has aged out, because when I went to try it again, the first half-inch inside the tube had turned into solid gum. Yes, it cures inside the tube and not outside.
Other than that, it seems like good stuff; I may pick up another tube and give it a second chance. Who knows? It might be useful in a plastic extruder or something like that.