We've had wool blankets, fleece w windproof shell and a TADV brand technical fleece blanket. All are useful and pleasant in and out of the tent, but are somewhat bulky depending on how you are getting into your camp (driving, sledding, snowmobile). As far as insulation with your plan, it makes sense to me only if you have a solid high R factor mattress setup under your open sleeping bag quilt system. (or a solid pine bough setup, etc).
We let our stove burn out fairly early as we head to bed and I sleep w my bag zipped up to between my knees and waist, necessitating wearing to bed a primaloft parka, fleece balaclava and fleece mittens (anything less than about 25F overnight)...sometimes it works wonderfully, other times, w/o reason I toss and turn fitfully all night long.