Well, Murray, given your definition of "unknown guitarists," I don't know if Michael "Hawkeye" Herman counts or not. He's far from unknown among blues afficcionados, since he has won some awards and he composed the music for the play "El Paso Blue" (which I got to see in a U.W. production in Seattle before the show moved to Ashland, OR) and performed the instrumentals for the play.I was very much impressed with his instrumental work, songwriting, and vocals when I got to attend a workshop at NW Folklife Festival in Seattle a few years ago (1996?) and see the play. I mention him in this thread because had I not gone to that workshop I probably would never have heard of him.
Here are a few links: