I will say that a female Jem'Hadar/Klingon hybrid strikes me as improbable, but the last time I checked, hating something just because it's improbable is a particularly silly form of bigotry.
I doubt that the Founders created the Jem'Hadar out of whole cloth. There was almost certainly a natural form of the species, reproducing by natural means (albeit not necessarily sexual; there's a throwaway line in some fairly old ST novel, as I recall, declaring that some never-referenced-again character was "budding"), deriving sustenance by the quaint, old-fashioned process known as "eating," and not dependent upon an external source of ketracel white.