I just brought a business folder with me and a pen.
Some schools (like Pitts) provide you space to store your belongings (like backpacks, etc.) so that you don't have to carry it with you during the interview. I'm going to make use of it for sure for an early checkout from the hotel.
I'm sure if you ask the admissions office to hold on to your backpack, i'm sure they'll gladly do that for you.
And yes, this is one place where i won't carry my surfboard with me. I mean... they've compelled me not to
But if i'm going to USC for an interview, heck i'll see who stops me from carrying my surfboard with me. I might just take it to the admissions office and ask them to hold on to it along with my backpack while i interview. Same applies to Nova.