I'm considering including a transexual woman in the game I'm creating, one who has had the reassignment surgery. I've chosen a model that is a bit on masculine side of the range of women's faces. I actually hesitated, because there are many cis women who have been suspected of being trans because of a more angular facial structure.
It could work, depending on how you angle the story. In my first playthrough of WVM, I specifically chose Shauna to be trans, even though it's not a kink of mine. The story plays out pretty well that way, but I ended up choosing her to be a "real" girl on my latest playthrough, mainly for the possibility of pregnancy (after this was sorta brought up as a reality with Jamie towards the end of version 0.9). This way, the story with Penny becomes a bit awkward, since she has a very different emotional attachment to MC's backstory with Shauna. If you've played the game both ways, you will have noticed.
Another great VN with a trans character (as a possible future love interest) is
Apartment #69, which could be worth a look, just to see Nea's story.
Midlife Crisis seems to handle this topic pretty well, too, when the character or Tracy is introduced (default name; when she's about to be introduced in the story, you get to choose whether you want to include trans content, and you also get to choose her name if you don't want to go with the default) - you pretty much get to choose how you want to treat her from that point onwards (when I played it, I went for a more inclusionary path with her).
For me, a story with a good inclusion of a trans character has been that she (or he) has discretely revealed to MC that they are trans (or has "extra bits"), followed by the MC being OK with it, as if being trans is just as different as having freckles, a heart-shaped birthmark, or a butterfly tattoo. Preferrably, the MC getting to know the person before they move further.
I've also encountered a VN where this topic wasn't handled as well as I'd hoped (then again, that VN was pretty much chaotic, story-wise - if you're curious, it was
Family Affair), where the MTF trans character was either submissive or dominant in their relationship with the MC. In that VN, if you were giving the trans character a BJ, or accepting anal from them, the renders seemed to give MC a more pained/frightened look on their face, and the trans character a more dominant facial expression, rather than both of them finding the situation mutually pleasureable.
I think the fact that you already have friends who are trans does help with your perspective on how their situation should be treated in an adult/erotic VN, assuming you're treating your trans friends the same as you would with your cis friends.
If you give your trans woman character the right type of personality (not overly dominant, which is usually the case in VNs where a woman has more masculine facial/body features), the model you have chosen will probably work out just fine. With the right character/story treatment, the character model's looks isn't going to be much of a roadblock.
