Sounds like your best bet is to find a company that will make you a custom bag. I looked at Western Mountaineering and Marmot and both have bags that are 5'6 but not shorter. Western Mountaineering is down though and comes in at 1 pound 12 ounces while Marmot's synthetic bags are either 15 or 30 degree rating and are 3 pounds and over 4 for the 15 bag.
