Along with whatever you decide for your batting (and I would personally use the thickest poly I could find....have done one with really simple straight line quilting between vertical rows of 9-patch on point) have you thought of using flannel sheets?
Flannel sheets along with flannel pj's under a really fluffy quilt and I'm good for the night. I have scleroderma and I turn blue very easily. (Living in cool, damp Oregon really doesn't help........ ;) ) Good luck........