Well not quite a quilt in my case. I have a top bag. I'm just contemplating using it as a summer bag. Up to now its just been used as my inner bag in winter. I use a Synmat, so was wondering what if anything would be good to act as something extra underneath just to boost temps/comfort very slightly. Given that my summer camps tend to never seem to end up as balmy warm! Options considered so far: Reactor liner Thermartex sheet Some type of single? down blanket.. if there is such a thing. If its a faff or ends up with no weight saving I'll take my down bag, but if there is anything out there which is packable and would just add some comfort, then its a consideration. So what goes under your quilt?