Princess,
When I read the title of your post, I thought you meant you needed advice about how to be in bed with a man while pre-op without him suspecting anything. That is a topic I know something about, as I did have a lot of bed time with men before my anatomy was corrected. It was difficult, and tricky, and dangerous, but I managed to get away with it numerous times.
But after reading your post, I see you are asking something else entirely, and to be fair to those that have attempted to answer your real question with real answers, the truth is, there may be no real answer to your dilemma, I am sorry to say. Almost by definition, a penile erection is going to be perceived as masculine and be intrusive to a female minded person like yourself, AND a straight male. It is an amazing feat already to have one straight guy willing to overlook the obvious, let alone 3 guys in your dating pool. You are already more than usually fortunate in that regard, in both my experience, and opinion.
The unfortunate truth is that relief from this problem will likely only come from the usual pathways, namely T blockers, estrogen, and GCS. No amount of tucking, or taping, or pubic hair removal, or clothing options, or any other superficial 'fix' will do. Not for a dysphoric woman, that's why the treatment protocols are what they are, namely, T blockers, HRT, and GCS. Anything short of those, well, falls short of being a true remedy for your issue. Your issue was my issue, as it is still a lot of girls' issue on a site like this. I wish there were an easier 'fix' than that, but as you may have noticed, nobody can come up with one, not one that works, and works reliably. I am sorry you are experiencing your distress, but I envy your situation as far as finding willing straight males while openly pre-op. In my life, such men did not exist. In that regard, you are very fortunate!
So, no, I have no answer for you, and I am doubtful there exists an answer that will satisfy your needs other than those provided by the Standards of Care.
Good luck with your therapeutic journey going forward!
MissyG