If they said no, no is no. That is all there is to that. It doesn't matter if it's enjoyed because it's completely biological.
Saying no is most likely rather pointless if the girl is moaning or showing physical signs of enjoyment. The campus offers escorts at night for anyone and during the day it is just a matter of either being with other people or making sure you are in a rather public place (even if it means taking an extra 5-10-15 minutes to get to class)...
Some women are to be partially blamed for this. They know the area, they know what happens, and yet they choose to dress up in provocative outfits..
I also wonder what the % of hispanic people that got raped are... based on a paper I read a while ago, hispanic women tend to keep such matters private even if it occurs to them several times.