the fancy solution: US-made, custom high end stuff, expensive, but they will make anything you want:
http://www.nunatakusa.com/claim on home page:
Everything we produce is fully custom made to your specifications of size, fill amount and fabrics. We even work with you to custom design bags and down jackets that work for you.
cheap solution - get the shortest bag you can find that fits your specs but is rated a few degrees better than what you may get away if you could find the ideal bag. Larger bags are more comfortable anyway. Big Agnes makes a few very small bags, but they are those silly no-bottom bags that need to slip on a pad to work. My daughter used the Roxy Ann Petite in 2008, which then was the smallest we could find. Replaced that with the REI sub-Kilo, which is much lighter and warmer, although it is longer. Also more versatile as a proper unzipped quilt, which the Big Agnes bags just don't work for having no fill in the bottom.
