I would use thinsulate. Not the lightweight kind, the kind that goes in jackets. I used it in winter jackets and I have made sleeping bags(that quilted beautifully) for my grandchildren. The number 150wt(years since I bought a bunch of it) seems to ring a bell. I plan on ordering more this winter from the US. It is $20-22 a meter here at Fabricland for stuff so light there is not even a refernce number on it. I plan on making a quilt for my son who has an extreme case of fybromyalgia and needs warmth at times.