I am not sure if they still do the alumni tent or not. I looked on the alumni association's website and facebook page and could not find any information about home game tailgates, and I usually stay on the north side of the stadium.
As far as where the best place to tailgate is, I think it depends on what kind of tailgate experience you are looking for. If you are looking for more of a family setting, I would say the lots on the south side of the stadium are more family oriented. That is where they set up the fan zone (right outside the stadium between gates C and D) which usually includes free food, games, tents, vendors, etc., and always has loud family friendly music. That is also where they do the Bull stampede, where the players walk from the bus to the stadium. I personally like to have more of a party vibe at my tailgates so I set up in lot 4 (North side) where more of the students and younger alumni go.