I plan to start my thru in mid-Feb and am actually thinking about using 3 different sleeping bags. I'm from the desert so I am not accustomed to cold nights. And unfortunately, warm goats are forbidden on the trail. So I need a really warm sleeping bag initially. All of my bags will probably be Western Mountaineering as I am replacing what I have. I was thinking of being totally prepared like Tipi and starting out with the -25 Puma. I then thought maybe a 0 degree bag and later perhaps a 20 degree bag?? I would really appreciate your input on this!