I can't really say for sure, since I've never seen what the parking lot over there looked like during a previous convention, but the motel's parking lot is pretty big, plus there is some more parking space under the freeway as well. It should be able to handle the parking needs pretty well, I would think.
I'm not sure what parking would remain should those lots fill up though, since the only other parking is for the mall and the supermarkets... who might get annoyed if cars were left there all weekend. *shrugs*