Hi Lori,

The reason for wearing the jacket inside the bag is to make the most use of every item I carry with me, I want as little dead weight as possible. Temperature could be around -10C.
Since I need an insulating jacket to carry with me anyway, I would rather get a lighter sleeping bag and augment its temperature rating with clothing.
I am eying 40F rated synthetic Montbell, and it seems to be a good candidate if it is not going to reduce the loft of my clothing. With this approach I can go down to much lower temperature using lightweight bag. It would not be too many layers, and far from restricting blood flow.
I tried sleeping a couple of times without any bag at all, just a good insulating pad and synthetic insulation cloths and loved it, with a light bag on top of that I would be in heaven.