I rather think that if you’re the kind of person who believes in “Ubermenschen”, you would have no need of a word for a woman, whom you would think of as a priori an Untermensch, or not a Mensch at all.
My understanding is that the ubermensch is a person who is not constrained by the limitations placed on him by society and religion, and is able to achieve his maximum potential by creating his own value system. What definition are you using?
The translation into English as “superman” rather than “overhuman” has more to do with the standards of English usage when it came about. But, however, we must recognize that by the general cultural standards of the time it *would *be expected that the actively leading Übermenschen would be the men, with the Übermensch women by their side actively supporting. (Brings me to mind Ayn Rand characters: think Howard Roark and Dominique Francon – they are both Superior People but as a couple it’s clear who’s the one who wears the pants.)
I believe that to PatrickLondon the term has been pre-Godwinized, that is, he’s presuming the Nazi (mis)usage of the term is the default meaning.