This might sound sort of crazy, but I'm interested in finding a frame that would work well for long distance rides on mixed terrain (sort of a BMW R 1200GS Adventure motorcycle). Basically, something like a Salsa Fargo, but full suspension and slightly racier geometry. I've looked around at different 29er frames, but I can't find any frame with the geometry I'm after. Basically, I'm looking for:

21.5" Effective toptube
17-18" seattube
80mm rear travel
IS Disc mounts
Relatively long headtube

Thanks