Have you looked at UC Irvine? They have an undergraduate Honors in Stage Management program, according to their website. I would also look at UC Santa Barbara. They have a Design concentration, which includes stage management courses. UC Santa Cruz does not offer a specific Stage Management concentration, but they have a webpage devoted to students who wanted to pursue stage management and they have a recommended course progression: http://theater.ucsc.edu/programs/stagemanagers. I would also take a look at the specific curriculum at UC Berkeley and UC Davis to see if either of those schools could meet your needs.
As for UCSD, they have an MFA in Stage Management (as does Irvine), but unlike UCI, I don’t see a specific undergraduate concentration in Stage Management at UCSD, so it’s not immediately clear that UCSD would be a better option than UCI, or even UCD or UCB, for example. I would research that further, if you haven’t yet. Also, note that UCLA says, “Students interested in stage management should know that there is no directed course sequence in stage management.”
Good luck with your research!