Thre is a newer variant of "black paper" that is 6 feet wide and made of non-woven synthetics backed by waterproof membrane. I believe it goes by the name of RoofGuardII or something like that. We have used it under standing seam roofing and the nice part is that it is quite light but reasonbly strong. Given half the number of seams, perhaps there is water vapor issues to consider but it sure is nicer to work with.