Dudette Was Not Originally a Female Dude
One of the most common slang expressions in the Western world throughout the 1990s was undoubtedly the word "dude." It may have survived into current times because of surf culture or the Teenage Mutant Ninja Turtles, but it is still frequently spoken even now. It's a straightforward term that, in essence, merely means "man," though you can tinker with usage and context a little.
Dudette has historically been a much less common phrase to refer to women than dude. Once more, the Teenage Mutant Ninja Turtles are to thank for that one when Michaelangelo coined the phrase in the 1990 film. Dudette is not, or at least wasn't initially, the feminine form of dude, thus you shouldn't rely on an anthropomorphic turtle to be linguistically precise.
If you go back far enough, "dude" didn't originally refer to a cowboy on a dude ranch, a surfer, or even a turtle. Dude was a "fastidious man" in the 1800s. So, this individual was conscious of his appearance. The Old West also used the terms dude and dudine interchangeably to refer to the female form, which was known as a dudine.