Let's talk about the changes to the redhead for fun because I love looking at the way this attraction, and Haunted Mansion, have changed over the years.
Let's start by looking at the concept art for the redhead. Here's two different depictions from Marc Davis. They both show the redhead as much younger than she appears on the actual ride and has a very petite waist. The joke is pretty much the same in both pieces with the pirate being interested in the redhead and the redhead wanting to be noticed (though, of course, she's certainly playing hard to get in that second piece).
We get the same design in this miniature model as well as the life size model of the scene in the Burbank Studios in December of 1965.
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Here's a better picture of the figure. Notice she's still all dolled up with a heavy dose of make up.
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Of course, though, as you pointed out, when the attraction opened in 1967, she ended up looking like... this.
Obviously the joke about the pirates wanting the redhead remained from the early concepts, but the design of the redhead was certainly different from the original intention. She was no longer a young maiden with a petite, attractive figure, but now she was rather wide in contrast and had awful make up. Was this part of the joke to make it seem as if the pirates wanted a disgusting woman? It's very much similar to the kind of joke you see in a movie where a man dresses in drag and then another man pursues him thinking he's a beautiful woman. The joke there, however, stems from the fact the audience knows something the man on the screen doesn't know: that woman is a man! That isn't the case here, though, and rather the rest of the women are all ugly in their own ways, too, so the idea of the pirates choosing the ugly redhead over overbite or Tiny is an odd joke. It's not that the joke doesn't work if that's what they were going for, but it's something that's strange and definitely a deviation from what the original artwork shows.
As we can see here by 1974, the look of the redhead was already changed to make her prettier and stand out, no longer looking like a man in drag. It's definitely more in line with the original concept art, but to me it's always come off as if the redhead is a a middle aged woman who's put on a lot of makeup to try to look younger.
There is one last thing that should be discussed, though, and that's the Portrait of Things to Come. Located in the grotto, this painting by Marc Davis depicts a redheaded pirate with a beauty mark who certainly seems to enjoy creating **** in the hearts of men. Because of the backwards storytelling of Pirates of the Caribbean, confirmed now by the newest addition to the grotto, it's very safe to say this is the same redhead from the auction scene. Her figure is definitely very much in line with the first piece of concept art listed above and she's definitely much younger looking than the redhead in the official attraction.
So really, what's the deal with the redhead in all of this? She starts off young and seems to be far along in the design process, even having a full model created of her, then only to have her be an older looking woman who's not very desirable in the 1967 attraction despite the grottos of that same attraction featuring this very portrait of the same character who looks visibly younger despite being title "Portrait of Things to Come." Was something lost in translation when the actual animatronic was made? I certainly would find that hard to believe. I definitely plan on looking more into why she was changed but if anyone knows more, please do share.