Maybe try out a female avatar in Saints Row III.
Yeah

that exactly often comes to my mind. That game is so absurd with female main character
I'm curious how you find an extra few pixels immersion breaking.
that's actually pretty understandable. It's RolePlaying game. A lot of us play it differently then action games

You take that role. You see the world throu your character eyes and if you ever played HCRP then your character has thoughts and dreams of his/her own. Some characters can simply be unbearable for experience. Nothing strange.
Boundaries of what, virtual transvestism? You don't make any sense.
of your mind. Every experience is good experience. It is always shame one denies any just because.. he is told so, he is closed to new things, he is lazy...

It's not changing personality or pretending to be someone else. It's creating a new one, different then you know from everyday. From the first post it almost seemed you know how it works.
In any case looking for realism in a fantasy game is...well words evade me here but I'm sure someone can think of the correct term here.
ooo, oom, I know

Same as you create different character with different personalities to play as actually realities works same way. As people knows only themselves they experience mostly only one reality. Call it "real one". When it is nothing else then projection of any reality meets your own perception. And you don't call reality the Truth out there. You call that that perception of world outside.
And same it works with fantasies. Every book, every game, every single mind of other person (authors f.e.) creates another reality. With rules. As we have physical laws so does fantasy words. Different ones, but the same. So for your character there is another "real" reality. And for player there are two now.

But different properties of different realities doesn't make them any less "real" as they both are in the end just in our minds.