That last one would be perfect if it were available in North America. Apparently Raleigh UK, Canada, and USA are entirely separate entities who share none of the same parts. I found a couple similar ones though: the Sunlite TCO and TCO Piston.

I realize now why they don't make them as I pictured it. If the clamp weren't offset, where would the expander bolt go?

So, it's not really a straight stem I'm after, but rather one with the absolute minimum extension (+ a removable faceplate).