Well, I'm hopeful that my Steelers make your decision nice and easy and you spend the Superbowl at home, watching a family movie instead of watching my Steelers win their SEVENTH title... :)
But just in case, I would recommend you try to find a campground about an hour or two away, more likely to find a spot. Perhaps you can see how much it costs to camp at the stadium too... but I'd be willing to bet that will cost a LOT of money. I've seen ticket package prices for the game that START around $6000 PER TICKET for nosebleed seats... No thanks.