@CaptainXtra
If there isn’t naturally a female character in the story, adding one for a sense of diversity will make the character not ring true.
That said, if you read the original Expanse books, IIRC, volume 1 has only two female characters in it, and they largely exist as love interests or plot points for the male characters and only one of those survives to book 2. By comparison, the TV series had a much more fleshed out cast with a much more even balance, and some of the female characters in the TV series are some of the more interesting characters in modern SciFi - even characters with only a few speaking lines are incredibly well grounded in the story (in the TV version - the first book in the series was largely a puking space zombies thriller, with some Walter Jon Williams style space naval battles.
Any SciFi from the 50s will be remarkably similar, with even seminal works like Forbidden Planet casting only a single female character, whose role is mostly to “confuse the sailors” of the spaceship.
So, it your cast is all men, write the story. If some of those characters could be female, you can swap them out when the story is over, but unless there’s a reason with in the story for them to be female, or if there’s no reason in the character’s narrative arc to be female, then they’ll just be cardboard cutouts stuffed into the story for diversity’s sake.
And maybe that there’s no women in the story is, in and of itself, a part of the story.
Anyway, if you read Leviathan Wakes, the novel, then watch Leviathan Wakes the TV show, it’s kind of a masters class in how some fairly simple rewrites not only can expand the range of characters, but also create some truly interesting and engaging characters at the same time, which will only make your fiction all the more interesting.
For another comparison, read Rendezvous With Rama book 1, in which Clarke was just experimenting with female characters at all, and Rendezvous with Rama book II, then 3 “The Garden of Rama” and book 4 “Rama Revealed” where the story comes to focus on one primary character Nicole Wakefield and her … let’s call them “adventures” to avoid spoilers. Gentry Lee wrote most of those later works, and it’s fascinating to see how Gentry updated the storyline and crafted a female centered storyline from what was original an almost entirely male cast. And, to be fair, even Clarke’s original characterization was almost pancake thin for the first book. Except for two characters, most of the cast could have been replaced with robots on wheels with no more personality than a toaster. So, it’s kind of an interesting set of stories in that it started out hard SciFi and then gained a social perspective, which went on to become largely the focus of the conclusion.
All of that said, if you want to read some books where the female characters are integral to the plot, check out Walter Jon Williams’ Dread Empire’s Fall, or one of Iain Banks’ Culture series, like Use Of Weapons or Surface Details - those two books actually are pieces of the same story arc, so reading first one then the other will give you a great breath of interesting and very well crafted characters. But, as great as I think they are, they might “do you an injury”, as the British bookseller warned me when I bought them.