Are you a freshman? I’m not sure about sharing with your friend but I would think so, there’s probably a way to request somebody but is he in the same college as you? Also it’s hard to get a double, in the past it’s easy but not anymore. Mine had to share a triple.
Since you know somebody that will be going to UCSD, I guess maybe you are leaning to that school. Academically they are both comparable, maybe a slight edge toward SD.