you do what almost every other school does - limit the entry to x,xxx on a first-come, first-serve basis for free entry. For example, my son just started at U of Montana. The student section is limited to about 5,000/6,000 (whatever the number, it isn't important here). Every Monday morning the week of a home game, students can go to the ticket office and swipe their ID. They know instantly if they made the cut. If they do, they then swipe again at the gate. You can forego this by buying a student season ticket for $50 that gets you automatic entry for each game with a swipe of the student ID at the gate, plus he gets a ticket to the big rivalry game with Montana St. which is not included in the free ticket offer and a fee t-shirt.
So, SU could do the same thing. A full season ticket gets you into the better section and gets you a ticket to the biggest game on the schedule. Or, you can go the weekly swipe route for free, but take your chances.