Competition should be over around 4pm. If we get a really good turn-out and if something unforeseen happens, like broken cars, an oil spill, rain, thunder, etc., it could be later, but it is unlikely that competition goes past 5pm. I don't recall when the banquet typically starts, probably around 6:30pm. You'd definitely miss that, but competing is definitely possible. Since Nationals takes place at the Lincoln airport, you can get from grid to the terminal in no more than 15 minutes. There is an 80% chance that you don't drive fifth heat and a 50% chance that you don't drive or work fifth heat. Even if you have to work the fifth heat, you might be able to find someone from the fourth heat who is willing to switch, although nobody would be excited doing that.