In reply to Sarah Ryan:
Unfortunately good bags aren’t cheap. I’d go for around the -15deg c rating unless you sleep cold. For Scotland avoid a narrow alpine style bags as you will be in your pit for hours and hours so being able to move and wriggle makes a huge difference. If you go the lighter bag but wear clothing route, again a roomier bag helps a bit.
I dont find the extra clothes route help sitting around stargazing in mid winter, if it’s cold enough to need a good bag, the extra layers aren’t warm enough to doss around in for me.
Some manufactures make to length or short length.
if cost is an issue keep an eye on a popular auction site but accept the bag might be too long.
Post edited at 18:30