In terms of character or presentation, are there things that are "off limits" for a female magician? Or things that would harm a woman's ability to get work? I was watching a number of videos of stage magicians while doing a little research, and it occurred to me that the characters or presentations by women are all within a fairly narrow range, while men seem to be able to get away with a lot more.

Let me give you an example. Dan Sperry has a kind of dark, Marilyn Manson meets David Copperfield character. It's edgy and alternative. Penn Jillette is loud and outrageous. Teller is silent, quirky and wryly amused. But I don't know of any female magicians that are on the extremes of character. Female magicians seem to have a much narrower range, and generally come in characters that are either sexy, mom-like or "inside baseball" funny, not outrageous funny.

Can men get away with characters that women can't? Is there a subtle sexism in what's "acceptable" for male versus female magicians?

I would never do balloon swallowing even though I think it is very magical. (The sexual innuendo is a problem for me and even if I did not have a problem with that, I am not the age or body type that could make that anything but horrible if I did choose to do it.)
Some Gals do and get a great reaction.

Do what suits you and see where that goes. If you feel something is not working for you, you can always step back from that. I've tried several things that did not work and I quit doing that. No harm done. Your tastes will probably change over time anyway.

There are so many Magicians that are so similar. One thing that Women have going for them is that they are different, so we shouldn't try to become all alike as Women Magicians.

People choose to hire or not hire for their own tastes. You can pick material to stay within certain guidelines to be more commercial in specific markets (just as Men do).

-Mary Mowder

Nothing is off limits.

I believe the lack of extreme female characters has more to do with the overall lack of female magicians than anything else.

The truth is that the vast majority of male magicians fall into the narrow character range you describe. Percentage wise I'm not sure there'd be any difference between; narrow and extreme performers... and, male and female performers. There are very few extreme characters (I prefer to think in terms of distinctively defined characters) within the vast numbers of male magicians that are out there so you'd only need a few female magicians for the percentages to be even.

And I can think of one extreme female magician... Vicki Leyton who works the show bars of Benidorm on the Spanish south coast during the Summer.

If you're a comedy female magician - like the great JUDY CARTER during the 70's & 80"s...then, ANYTHING goes!
(i.e. After plucking two sponge balls from her pants pockets - She says something like: "Oh! my Ovaries!")

But in general, Today, women magis might want to avoid performing Goshman's "Ding Dong" sponge ball finale, for example.