I've used a fleece sleeping bag with a pad or good underquilt down to mid 50s pretty comfortably when dressed warm enough to stand around in those temps. Living in Alabama, I experience similar temperatures to what you experience. If you have trees in your yard at home or other ways to hang close to the house, I would suggest testing items that you currently have or can get your hands on to determine what you need at certain temps. At 70F+ you won't need much of a top quilt. A bag liner or sheet will suffice.