Make your own quilt. There are kits, but you can just tape the perimeter together and use a tagging gun for stabilization, or the yarn bits. One of the ideas behind quilts is to make them somewhat disposable so that when the loft starts to be lost you toss them. Not really how I roll, but they have a point. Quilts are less likely to wear out anyway, since you aren't lying on them so if you don't like that idea, it isn't required.

I don't really buy the whole tarp thing, and then Jardine got really ill with lime disease. But a very simple single wall tent is pretty much the same weight.