With a double wall tent I have more than a few times brought my stove inside the tent.... Yes inside. Sure someone will chime in that it's stupid and dangerous but having extensive experience doing this if done in a safe manner can make the inside of the tent toasty warm and also dry out any wet clothing. Of course this is only for short periods and NOT for sleeping.

Already mentioned... sleep with hat on. Good pad and a bag with a real rating of 20 should keep you toasty. A rating of 30-50 just sounds like a crap bag to me. Invest in a better one and sleep like a baby. A single pad is plenty if it's a good one. Having slept on a ton of glaciers with my single pad and 20 degree bag I have never been worried about surviving a night.