I parked at MN fairgrounds last year. Tailgating was reduced due to very cold weather. The parking area, however, is huge, so you should have plenty of room for tailgating. It was policed, so underage drinking would not be smart. Shuttle service was exceptional ... there were always 2-3 buses queued up waiting for fans at both ends. The ride was about 10 mins.
I think I took 35W north of downtown, east on hwy 36, then south on Snelling. It was very easy to reach.
Enjoy your trip ... may the outcome be improved from last year.