Hayward area best Smallmouth Taxidermist
Although, not in Hayward, and you likely have found a taxidermist by now, I just went through the same search. My daughter caught a 21.75" Smallie near my home this spring, which is the biggest smallmouth I've ever witnessed on these waters. We made a quick decision(regretfully) and released the fish, only to realize later just what we really had in our hands. Luckily I took several good photos and found a taxidermist that paints the nicest smallmouth I could find. He also had a mold that fit the slender shape of our fish to a 'T', and has been a great guy to work with. His name is Daniel Blackstone and hails from Florida. Again, I'm sure this isn't exactly what you were looking for, though thought I'd share the reference nonetheless.
Here is a link to his business Facebook Page with some pictures.