Slept in my first hammock tent (Hennessy) over Memorial Day weekend in Ohio. I had a light sleeping bag, and I think every night I ended up pulling it on in the middle of the night. It wasn't really cold, but I was glad to have it. I also had a pad to sleep on. It just got in the way. After a night or two, I took it out. I'm sure it'd be valuable in the cold, but it was a very pleasant weekend. And Ohio in May is cooler than SC in June/July. I'd have a light bag, just in case, and maybe a change of warmer clothes for the night time, but you will almost definitely not need to worry about any under-side insulation.