I would agree with Vlad. It's far from ideal. However, let's walk through all the options to cover all bases. Others feel free to disagree with me:
The pros and cons as I see them:
1) She would be very lonely but safe if left behind with the parents.
2) A new home with someone to love her and spend time with her is the ideal solution so I agree. A concentrated effort should be made to do this for her sake.
3) There is no guarantee she will find a new home...though the effort should not be stopped, even after going away to college because...
4)...if you brought her with you, nothing promises that you won't be busted for keeping a rat and told to 'get rid of it immediately' or be kicked out yourself. (We tried to help a young woman in the same situation who got busted and was pushed to keep her rat in sub freezing temperatures in the car overnight).
5) I can tell you that a cage topper plus 10 gallon tank won't be allowed. The whole reason they force you to use 10 gallons, is to discourage you from keeping larger pets like rats. So don't bother asking for special permission.
6) A rat can tolerate a smaller cage (10 gallon PLUS a cage topper being considered smaller) if you are dedicated to spending a LOT of time with her and letting her run loose. Several hours worth of time daily if possible. In other words, she will be a bigger time responsibility if she goes with you than she is now.
5) Most rats from my rat expert friend's experience won't even use the 10 gallon section if they have access to a cage topper.
Illicit option: The beds in our dorm were bunk style adaptable and very sturdy. We found if you wanted to, you could turn the frame upside down and create a study nook underneath the extra tall bedframe while you slept on top. My husband (boyfriend then) filled the open space with milk crates crammed with his books and clothes. It created a large secret cubby space behind/under the bed. In my less than respectable days, when hanging out illicitly after visiting hours, it was a handy hidey hole when the RA's popped in unexpectedly. I'm not saying this is a good idea. After all, rats don't know how to be quiet just because you need them to do so, so chances are you'll be busted pretty quickly. Though you could constantly play music or something to drown out the scratching and chewing. Someone's going to...uh...rat you out before too long. Especially in a girls dorm with a guaranteed selection of catty gossipy immature rat-phobics living with the more laid back girls.
If you're good socially, you could always make good friends with the RA's on the first day and see if they would be willing to look the other way for the next six months to a year that would be the remainder of her lifespan as long as you do your best to remain circumspect and careful on your part about her existence so the RA's don't get put on the spot by their superiors.
6) While you might be tempted to get a second rat to keep her company, now you have twice the responsibility with 1/4 of the space needed instead of just half the space needed. Plus the companion is going to be younger and therefore with you much longer.
So yes, you can try keeping her, but it would be a temporary set up at best with the constant risk of exposure and abrupt eviction.
Did I miss any angle?