I honestly don't think there would be enough interest on campus. Some students would wander over there for a while but it wouldn't be quite like these other little towns where it's the most important thing ever and there's tons of people in the vicinity tailgating.
You're underestimating our campus culture, trust me they'll show up in masses... also, Gameday is open to everyone and an undefeated UM will draw the crowd.
I'm on campus all the time. I see a lot of orientals and nerds. Gameday requires thousands of drunk rednecks who spend all week camping out, making signs, drinking bourbon and corn-holing everything in sight. Whoever schedules Gameday in Coral Gables will be out of a job the next day.
I went to the last Gameday that involved Miami/FSU(up in tally a couple of years back), it's an overrated experience. I doubt kids are going to commute to campus just to go to that, and you can't rely on the resident kids to show up early on a Saturday morning, when they are most likely getting ready for the game. Even when Miami was the kings of the sport, Gameday rarely showed up.