I like the idea, exept for the cutting the frame part. OldSub has the right idea, go for a long set of bedsides, then make custom fenders to fit. I beleive there are wide fenders available in 'Glas, you could trim the openings to fit the 20s. Or alternatively, find a couple of sets of decent steel fenders, then do a bit of cut and splice to make a wider and longer set, which would allow for a larger opning while keeping the overall proportions in scale with each other.
