Before heading out on any overnight trip make sure your sleep system will keep you warm, especially when you are testing the lower limits of your gear is being pushed. Before leaving for my 140 mile trip from Chattanooga to Nashville, TN, I am laying out open while the temperature is 21 F in my HG Burrow 20, Thermarest Prolite, GG 1/8 Thinlight, and DIY down pillow. Total weight: 42 oz.
Just to be sure, I have on my Rocky polyester bottom baselayer, smartwool socks, Baffin slippers, my MH wicked lite, and marmot reactor 1/4 zip. Not only am I warm enough to make it through the night, but I am feeling toasty!