I'm all for live and let live, but you are ridiculous. Are you really going to use Freaky Friday or some other magical body swap fiction as the basis for your reasoning?
There's a disconnect between reality and what some of you want to claim is the truth. Believing you're two or more different people is a mental illness, but by your rationale it shouldn't be, it's merely what someone knows they are. Changes to the DSM surrounding gender dysphoria was a political move, nothing more, nothing less. If people with multiple personality disorder had a sufficiently large political bloc, you'd see that removed as a mental illness and given protected status as well.
Beyond that, everything you're talking about is societal and based on conformity to gender roles. If an XY human likes dresses and makeup instead of football and beer, that's just a man who likes those other things, not a woman. I don't particularly like football either, does that make me partially female? Should I start using the ladies room?
I agree with the idea that you are what you, no matter how you were born, and should be accepted as is. Whether that's a man who likes women, a man who likes men, or a man who likes wearing heels and a skirt. Transgender defies that, and insists that you actually CAN be born incorrectly, and should be fixed by modern medicine. I find that to be damaging and insulting to people that have to put up with your bigotry in the name of trying to make yourself look compassionate.