It has been my experience for late winter/early spring on the AT that I have never needed long john bottoms. But, I have a really good sleeping bag so I have not needed anything extra for my legs at night. If it is cold when you get to camp, let your rain pants serve as an extra layer. This way they serve 2 functions. I only need long johns for hiking if temps are way below freezing (single digits and below). But as they say, YMMV.