Current UCSD grad here. There is one way I know of to get around that, which is to look for a roommate wanted offer from a current campus housing resident. You're still taking a chance, but it could be a little less blind. You may be able to find someone by joining this:
https://mailman.ucsd.edu/mailman/listin ... using-op-l
or less frequently, this:
http://hds.ucsd.edu/hsgaffil/roommate/mainmenu.aspx
or even less likely, this (UCSD network only):
http://www.facebook.com/home.php#/group ... 557&ref=ts
FWIW, I'm a current Miramar resident looking for a female roommate come summer, if anyone is planning on moving here early.
On another note, it's interesting to hear that you have no choice in who your roommate is going to be. Who told you this? The housing policies are in a state of transition (long story...) and people at different levels of the administration have different ideas of what is actually applicable. It's a mess.