LOL! I know exactly what you mean. I used to be able to sleep in a mummy, but in my old age, I just leave it unzipped, so my legs can move. Plus, my Mtn Hw bag is so warm, i need the ventilation.I for one can't sleep in a mummy bag because I sleep at funny angles. Does anyone know of an extra wide bag that does well in cold weather.
This.The Army's 3 piece sleep system will forever hold a place in my heart
Hot? Use the lighter shell
Cold? Use the thicker shell
Wet? Waterproof shell
It has never let me down
You might also consider a quilt, but they can be pricey for good down. Alternatively, I sometimes use my mummy bag which is a 3/4 zip as a quilt and there is more than enough room (I'm 6'4 210 lbs). @John had a good suggestion too, can't go wrong with military surplus for the price.Definitely looking for a rectangular bag. I have a flannel lined coleman bag now and froze my butt off on my last trip to the desert.
Thank you for all the great answers.