I'm hoping we can find parking somewhere close by for cheap by 11:30-11:45 and walk to the stadium by 12
If you can get your hands onto a parking pass (which usually go for $50 but WELL worth it) then I say do it. If you plan on finding a parking spot that late then it simply won't happen. If you leave that late without a parking pass, the traffic will be absurd and you'll be lucky to find a parking-lot that is not pre-sold willing to cramp in some extra vehicles. Your best bet at that point would either be a parking garage or simply leave hours before the game to get a parking spot.