I'm looking to make a super light, but even more importantly, small and super packable quilt, mainly for summer use in Minnesota and Wisconsin. I'm looking at nighttime temperatures in the 60s. I will be using the quilt inside a bivy. I have some experience making synthetic quilts, but I'm thinking to go with some amount of down and M50.
I have two questions. First, how little down can I use and still create an advantage over a few layers of M50? I'm doing one to two night trips where covering a lot of miles quickly and easily is more important to me than being totally comfortable, but if I can make a quilt that will pack down small and still be warmer than a sleeping bag liner, I'd love to do it. Second, how small can I expect a very light down/M50 quilt to pack down to? I've been carrying a Lafuma 40 degree down bag that when in its stuff sack is somewhere between a softball and a football. How much smaller than this is possible in a quilt?