I thought of Blanche, Gail, and Lane. Also, if Steph is accepted, why not my cousin Les (short for Leslie)? I have no idea how a person would go about collecting all these names. Sounds like a huge challenge!
It was a huge challenge, and still is apparently :) I added all your names except Gail, which I think is two syllables: GAY-ull. If Gail is accepted, then Dale, Gale, and Dail would have to be as well...
Well they wouldn't as Dail isn't a forename and Gale is misspelt. You did miss Sian (pronounced Shaan for those heathens who think it's pronounced Sigh-Ann)
Names now out of fashion include Merle, Vi, Nan, and Nance.
I know women who go by Fi, Dan, Shell and Cam (shortenings of Fiona, Danielle, Rochelle, and Camille).
I'll add another vote for Gail (Gayle), as many others have, as it's a one-syllable name in my local (Australian) English, as is Dale.
You've also added Mauve (which exists as a name, but is fairly obscure) in response to a suggestion of Maud/Maude, which is a much more common name.