Peter, The difficulty in reproducing "Sachsenberg's Diamonds" on the D.VIII using the WnW 32011 decals is not so much fuselage shape as it is size of the diamonds (roughly 8mm on the diagonals on the 320011 sheet)
Many profile/illustrations I've come across (including the MikroMir illustration) seem to assume that a regular pattern of evenly-spaced diamonds was used as a template, and simply "cut-to-fit" the sides, top, and bottom of the D.VIII, like a modeler would do if covering all sides of the fuselage from a printed sheet of Black/Yellow diamonds.
If, on the other hand, one assumes that the pattern was regular on the sides but altered on the fuselage top & bottom (like his D.VII) then I think fitting the 32011 decals to the D.VIII might not be so much a problem. Some of the D.VII profiles on the net show only TWO full rows of diamonds on the fuselage sides, which match almost EXACTLY the diamond size on the WnW sheet. I know, because I just pulled out the WnW sheet & compared it to the MikroMir fuselage
I've read of but never seen photos of Sachsenberg's D.VII with (faintly visible) diamonds and a "face" of so some sort on the cowl.
Hope this helps,
Rob