Here to help....
Yes, you can tailgate conveniently in a parking deck within meandering distance of the stadium. It is close, affordable, accessible and uninspiring. There are plenty of other options.
Most UNC STHs have a pass to one of the lots on campus. You can usually find one of those on the open market. Best lot for such activity is by the Dean Dome (easy to get to, lots of people and the admissions office has ensured that no Statefans will be there). Other than that, most of the lots on campus are all pretty good; the closer the better.
If not, then there are several pay lots within walking distance of BKS. The one I recommend is run by the "Friends" Society. If you are coming up Raleigh road from the 54 exit off of I-40 (exit 273) it is on the immediate right, right as you get into main campus. Come early (two hours before kick is "early") and you should have no problem finding a rental spot to tailgate. $20.00 is market rate.
From the South (coming up 15-501 from Pittsboro, and then don't exit to merge with 54 (instead stay straight up the Hill on Pittsboro Street), same thing $20.00, two hours before gameday and you can open air tailgate.
From the North, good luck. I'm sure you can rent a space for $20.00ish, but it will be tucked into the side of someone's apartment building. The better options are from the South and East.
If you've never been to Chapel Hill before, at least walk up and down Franklin Street an hour before kickoff.