If I were coming from out of town, I'd be tempted to camp there myself (I normally tent camp). Living only 20 miles from the rally site, I'll be commuting. Alas, I live on the north side of Knoxville, so I'll have the same traffic I would were I staying at Big Ridge or Norris Dam SP.
Rush hour traffic means different things to everyone. It's really not all that terrible in Knoxville compared to bigger cities.
Yeah...Melton Hill is still the closest and easiest place to camp I suspect. Weekends may be pretty busy there, but with a reservation, it shouldn't be a problem. Sunday night the crowds will disappear (true for State Parks as well), and it will be even more pleasant.