Nice topic Simon.
I feel the same way too, I often go in and out of many different categories, and it's really interesting to see the various reactions.
I am usually either out as male, though I don't always pass, or I am out as female. It's funny how people hold doors open for me, treat me all nice and stuff while I am out as female; or how some people just ignore (or study me) when I am out as male and not passing.
I have pale skin, but I am not 100% white, so it's interesting to see how people who are visibly not-white sometimes just assume that I am another white person and that I don't really get everything they're about, and how it's also interesting to see how sometimes other white people just assume I am just like one of them. There's a difference between how people can treat and relate to me if they know I am not fully white -- at least until they forget.
Another thing I kind of blend in and out of is being viewed as a Muslim sometimes. While I am not Muslim, we're supposed to cover our heads at Gurdwara, so I usually just wear a scarf kind of like a hijab when I go. I usually stop on my way over to get coffee or something so I can break a twenty, and I've had people glare at me, call me a terrorist, accuse me of being in al-Qaeda, and sometimes even have men avoid eye contact with me all together while I am paying for my coffee. Then, lol, when I am out without a scarf on, other (white people only from my experience) sometimes talk to me about how Muslims are taking over the country and how sexist they are.

It's like. . . if only you saw me yesterday we wouldn't be having this conversation. Sometimes it's kind of nice, if I run into actual Muslim ladies, they get
really excited and "salaam alaikum" me or like excitedly wave to me from the other side of a room, especially if I am in a place where there's not many of them around. Even though I am not Muslim, I can really understand how they feel about things sometimes, it's like it's nice knowing you're not the only one around. If I am out and see someone who kind of has trans characteristics, I think I feel the same way that they do, though I don't go up to anyone I see as trans since I don't want to out anyone.
Sometimes I feel like I am walking on a tight rope between so many identities. People see me dressed one way and make all sorts of assumptions about my life, my ideology, my identity, and that's how they decide to treat me.
While it is kind of frightening to know how easy it is for people to make assumptions, I think it's kind of a good thing for me to experience. I feel like experiencing both sides to some aspects of life makes me more cautious when I see people to not make assumptions, and to really try to recognize when I am treating someone differently based on how they look.