I guess I am a little too late to comment but it seems your on the right track with letting her dress you and teach you mannerisms to help pass. But my concerns are ( from my own college experiences thought I did not dress then) (a) College dorms are very busy places and if you are not out yet nut people there know you (and I'm sure they probably do) no matter how convincing you are, chances are high that someone will recognize you, (b) I don't know where on campus the meeting will take place bit you will at some point be walking across campus to the meeting or to a vehicle to get to the meeting and again that means crossing paths with other students.
I know when I attended college even though I didn't know I personally didn't know people it seemed like everyone was a friend of a friend so when something did occur it spread like wildfire across campus and eventually everyone knew about and in a relatively short time.
So my suggestion is to let her dress you up and practice the mannerisms and after that if you are comfortable with the risks then I say go for it, but if you even have a shred of concern that you will be found out and you think the risk and repercussions will be too high then I would say not to do it. I'm sure that is not the answer you were looking for but hers and your safety needs to be of paramount concern.
