I dug up the table Cosina provided in the Voigtlander Bessa R2S/C manual. It shows whether the image will be in/out of focus at several focus distance/aperture combinations for a Nikon RF lens mounted on a Contax RF body or a Contax RF lens mounted on a Nikon RF body. Side note, while all lenses in the Voigtlander SC/S lens lineup were designed for Nikon S-mount (states that clearly in the little manual included with each lens), Cosina labelled the 35mm and wider lenses "SC" because DOF "hides" the focus error at all focus distance/aperture combinations when the lenses are mounted on a Contax RF body, but labelled the 50mm and 85mm lenses "S" only, not "SC", because DOF doesn't "hide" the focus error at all distance/aperture combinations. This table shows what you can expect when 50mm and 85mm lenses of one system are mounted on a body of the other system. Infinity is in focus at every aperture (because the register is the same). This wouldn't be possible if there was a 0.31mm difference in "body thickness".
x = out of focus (point of focus is outside the DOF)
O = in focus (point of focus is within the DOF)