Yes, I was aware of the Zeiss 21 floating element design. I guess I was trying to say there was more than one way to accomplish the infinity issue. While most floating element lenses do have infinity adjustment, you are correct, I tend to adjust infinity by varying the mount thickness since I'm custom maching the mount in the first place.
In the above case when you can't make an adapter any thicker, shimming is an obvious choice, and if one knows how, lens adjustment is possible. We're talking about .001s of an inch. In this scenario, .001" shim thickness would be the way to go.