This is something that comes up often in professional work environments. As an INFJ, the way I like to be a team leader is by focusing on the strengths and weaknesses of team members, providing avenues for them to grow, and also finding ways to address their shortcomings.
Sometimes, gender identification can get in the way. I wish I could claim that I was able to entirely objectify my Fe goals for my colleagues, but sometimes this can become 'thwarted' by baser instincts.
What I try to do in this situation is emphasis focusing on the wants of the individual that is distracting me. So for example, if I find that I am thinking in a gender specific way about an individual, I will instead try to think about how their recent actions relate to the kind of environment they want to work in, their career goals as expressed through their work, etc.
By focusing on seeing things from their perspective, placing oneself in their viewpoint, one can diminish the role that perceived gender has on the model, because first-person perspective, in my world, is far more gender neutral than second-person and third-person perspective. Putting yourself into the 'first-person' of others may lessen the impact of gender upon your perception of other.
I realize that I have answered your question from the perspective of someone clouded by typical sexuality, as opposed to your more interesting situation of having a tenuous relationship with the issue. None-the-less, I think the concept of perspective might work for the issue from both directions. In one of your earlier posts, it sounds like you are doing this. But perhaps if you start with the questions of 'what is x thinking', and arrive at the question prior to identifying gender, you will begin to neutralize the bias.
It is also possible, though, that your fluctuating emphasis on one sex or another is helping your subconscious deal with concepts of identity through traditional fantasy. It may need to deal with identify at that level even if your intellectual side has advanced far beyond. In that case, maybe a better answer would be to let it indulge itself and then, on top of that, engage your intellectual element to probe deeper into the fantasy beyond the fascination with a gender role. In that strategy, you would ACCEPT the fixation and then override it with more interesting questions. Almost like the way biologists tag animals and then follow them, you would tag your fantasies and then follow them to ask meta questions of them.