I am a connisieur of very few things, but a good night’s sleep is definitely among them. More important than your sleeping bag is a good pad; I’ve tried everything from ultralight models that wouldn’t make good butt-floss and car-camping monsters with more padding than Mama Cass.
The award-winning Exped DownMat 9 Deluxe is a lot like Mama. Insulated with 700-fill down and rated to -40F, the 9 is for 9cm of loft – that’s 3.5in thick for us Americans. A roomy 76x26in sleeping area catapults the weight to a hefty 3lb 4oz including padded (for pillow use) stuff sack, which doubles very effectively as a low-effort pump to inflate the pad without using your nasty moisture-laden down-dampening breath.
The DownMat packs significantly larger and heavier than lesser pads, but if you’re heading into serious cold or just don’t mind the extra bulk you should gladly make the tradeoff, and you might be able to make up some of the difference with a lighter bag.