I guess I thought the main concern was coupling to a parallax corrected finder, as opposed to the rangefinder itself, but that is a bit ambiguous in the question posed. Hyperfocal focusing works well on lenses this wide.
Originally Posted by Ole
I do use the L bodies for longer lenses, but focused at infinity for wide-field astrophotography, and hyperfocal for landscapes. They are great for astrophotography because of the light weight, mechanical shutter, and the 1:1 brightline finders for the longer lenses are the best I've seen for composing on the night sky. Both eyes open and many more stars are visible than through any SLR I've ever seen. I use two at a time on a driven mount so I can shoot twice as many time exposures, and on different parts of the sky with different focal lengths. At US$69, I can also leave a body or two dedicated to astrophotography film without feeling like I have spent too much on a "single purpose" body that doesn't see a lot of use. They do end up getting used for other purposes, like the wides and a pinhole body cap I made.
I own and really like both the 15mm and 21mm C/V lenses. Both are on loan with a Bessa T body to a friend who's a dedicated SLR user in 35mm and 6x7. He's very particular about framing his 'chromes. He called last night and after some initial reticence about their usefulness on rangefinders, he's having a blast using them and asked for an extension on the loan to do another project.