FWIW, I think it's a gamble with the floorless tents if you don't have the burlier sleeping bag fabric, especially for multi-day trips. You could toss on a bivy sack, but now you're adding more weight. I'd also be concerned if you like getting out in the wind, with no snow skirt, a pyramid/ish shelter is hard to keep the spindrift out of. You can really sink in the tent edges themselves and pile on snow, but then you loose usable floor space. I'm thinking about sewing a tyvek skirt on a BD betamid/megalite - would add minimal weight, but I think it would do the trick. Less snow blown in would help you keep the down intact as well, although larger concern is the snow you're laying on / what gets between your pad/bag.