Not looking to de-rail the thread at all - also: this is not about me, but: I shall use myself as an example, still:
I suppose one could say I was "authentically living as" an upper-MC corporate executive these days. I suppose I even "pass": I have the house and the car to go with the title. My hair and face are always nicely done - but in a "definitely not TOWIE" kind of way. I have the frequent flyer status and hotel loyalty scheme ranks that befit anyone of my status. When at a restaurant, I know which wine to order and how to make small talk about it. I read the business press and am always well informed about economic affairs from the point of view of a "gazillion dollar corporation". I look the part. I meet my business partners at the local golf club on a weekend sometimes.
And yet, I was born working-class, grew up on a rather rough estate. In my personal life, I prefer a pint over some fancy vintage. And on a weekend, I wear jeans from the high-street and my hair in a pony tail. I personally believe it's fundamentally wrong that some people - especially my own bosses, but even myself - make obscene amounts of money for ... basically: still a mystery to me what I actually do! The only reason why I moved out of my last place was because I realised my colleagues would be utterly terrified to come to my neighbourhood, and "entertaining" was expected.
Why I'm bringing this up: in some ways, I guess, I'm not that different from someone "authentically living as" female but having been born and brought up male. Or vice versa. Somewhat snarkily, I suppose I could be considered "trans class". I "pass" usually - but then, there are always these little moments that remind me I am not quite the same. When my (all very toff) colleagues speak about their childhood and refer to their parents as "mama" and "papa", for instance. When people, in genuine exasperation, bitch about the complications of inheritance, and I find myself thinking "yeah, sounds ... not fun. Never going to happen to me though, so, all good!"
Personal opinion: if you can't even properly "transition" in terms of such an obviously human made thing such as social class, I doubt that "authentically living as" something as fundamental as actually biologically different could work much better!