I am planning to do the Minnesota Frozen Butt Hang in late January next year. Hammock is a Clark NX250. Lows could reach 30 or 40 below. Anybody know of a full underquilt made by Jacks that can cope with that kind of extreme cold? Or would it be possible for them to custom make one? Just looking for ideas on the best way to go here. I already own one of their torso length 0 degree quilts and recently aquired a Mt. Washington 20 degree. Been completely satisfied with their products and would love to use Jacks again if possible.