I have met 3 guys in the Sierra Nevada Mountains who said they were doing 18 to 22 mpd. All of them had really light setups, but one actually showed me his sleeping setup. He had a really light one man single wall tent no floor(I don't remember what kind), tyvek ground cloth, a 3/4 length sleeping pad, and a sleeping bag that was essentially a shell, like half a peanut shell. He basically recognized that the down that you are laying on is has a much lower R value then the rest of the down bag. I think he said that his sleep system, tent, ground cloth and backpack was around 4 lbs. It seemed to work for him, but then he was dining on peanut butter and skittles on the trip we met him on. One of his pals was trying pound slabs of butter....obviously they are not cooking. I think I would go with peanut butter and nutella.