Is it really fair to call this “gender bending?’ At least in the way we use the term today?

The only reason we should be biased against the hypothesis that this woman soldier was transgendered is that transgenderism is statistically uncommon. Some mild degree of skepticism is appropriate, therefore, because transgendered people are a comparative rarity.
HOWEVER, we should be wary of unreasonably excessive skepticism, because although the transgendered are rare, they are not “vanishingly rare”. Thus, we should demand pretty solid evidence, but “this woman was probably transgendered” ought not be taken as an extraordinary claim requiring extraordinary evidence (the phrase that James Randi or Penn and Teller would apply to telekinetic spoon-bending or alien abductions).
No one knows with certainty what small percentage of the population is transgendered, but such people are without doubt vastly more numerous than, for example, Siamese conjoined twins. (I recently read that there are only eight pairs of post-pubescent conjoined twins in the entire world — that’s 16 persons out of a global population exceeding six billion, even with modern medical care that can improve the survival rate for non-separable twins!)
But suppose someone found an authentic Revolutionary-era letter containing an account of a “two-headed man” — i.e., a dicephalic pair of conjoined twins, like the celebrated modern sisters Abigail and Brittany Hensel.
A lot of people would be quite prepared to believe the account — “Well, I’ve seen TV interviews with the Hensel girls, so I know such a thing is possible.” Moreover, few if any people have ideological biases against the reality of conjoined twinning!
Looking at it from a purely statistical and medical point of view, however, the odds greatly favor the likelihood that the story was either a total hoax, or a wild exaggeration (maybe, in reality, the man had a huge benign tumor on his scalp that vaguely resembled a second head — that’s vastly more probable than dicephalic conjoined twins surviving past infancy).
And — just to spell out the point clearly — assuming we’re not clouded by ideological bias against the transgendered or other sexual minorities, then claims that a historic figure was transgendered ought to arouse significantly less disbelief than historic accounts of adult conjoined twins. (Many of these “two-headed person” accounts were probably “carnival frauds” attempting to cash in on the very, very, very few real-life cases.)

Honestly, I don’t know the full story of the women Barton talks about so gender bending may or may not be accurate. The woman may indeed have simply wanted to do something she was not allowed to do and dressed in a way to get there, all the while maintaining her female sense of herself. Or she may have been drawn toward such actions because she was transgender.

Gender bending and transgender are two very different issues and ideas.
Transgender speaks to persons whose internal sense of gender is dischordant with their observed gender. They may have male genitalia but experience themselves as being female. (There are some interesting studies involving children who were assigned gender at birth due to abnormalities but who developed a sense of gender that was quite different than that assigned).
Gender bending deals with challenging the roles, appearances, or even concepts of gender. Bending gender can range from drag to trasvesticism to Lauren Bacall to anything in between.
The way most commonly currently used, a gender bender might choose to dress in either gender – depending on mood or whim – or as androgynous, so as to make a statement. Their own sense of gender might be somewhat fluid or might be consistently male (for example) while their expression might be all over the place.
A gender bender might, for example, show up for a party dressed in a corset, flounced skirt, and biker boots while sporting a full beard.
Neither of these are necessarily gay. At points several 70’s rockers dabbled in the idea.
But in the sense that these women presented as men and dressed accordingly, gender bender is not an inaccurate term.

I am also aware of families which wanted “a boy” instead of a girl and dressed her that way and expected those things out of her…her identity (by her report) is as a masculinized woman.

I know a family that had fraternal twins and wanted one to be gay and one straight. They ended up with two straight sons that were comfortable around gay people… but the ‘gay’ one does seem to find it easier to connect with women (and married the prettiest woman I’ve ever physically laid eyes on).
Which I guess suggests that you can’t control the gender or the orientation of a child, but you can influence how they will interact in the world