I've sat outside at my girlfriends house in Charlotte in shorts and a tee shirt more often than not. Sure they could have a cold snap but if the event is the Championship final people know how to dress accordingly. Southerners do have jackets
Just lose the spring race. The labor day race will be good for everyone to get dialed in for the Championship. I remember when they ran the two races at Pocono about a month apart so it shouldn't be a factor