I just got back from touring on the Delta Heritage Trail in southeastern Arkansas and yet a couple nights got down into the upper 20's. (at least my water bottles didn't freeze this time) I like a 2 person tent so I can sleep at somewhat of an angle ensuring my toes and head don't touch the tent's walls as that's when I get really chilled. My 30 degree down bag keeps me comfortable at these temps but only if I wear some clothing to bed including my lightweight down jacket.
