1) it's San Diego
2) every B1G school has large alumni bases in Southern California. Do you actually think that 70,000 people from Wisconsin travel to the Rose Bowl? No.
3) saying "bottom tier of Big Ten travelling base" is a tad comical. This isn't exactly the AAC. We're talking about the co-best travelling conference in the nation. Being behind OSU, Mich, PSU, Wiscy, Nebraska, and Michigan State, doesn't exactly mean only 10K in San Diego.
I didn't say they'd have 50,000 fans there, either, but I'd bet dollars-to-donuts they'd travel a lot better than you think.