I have a Nunatak Akula, which was custom made for me (small woman) but doesn't fit me right. Since I had it custom made, I can't return it. I would think it would also work great for a child under 3.5 ft as well-- for the brave parent who wants to take them backpacking, climbing or bike touring but doesn't want to carry heavy gear.
Rating is about 10F
Down is 800+
It weighs 10.2 oz
It stuffs to the size of a softball
Has only been used once and stored lovingly unstuffed
It retails for $250, I'll sell for $100
The specs of a non-custom Akula: http://nunatakusa.com/site07/other_bags/akula.htm
Mine is narrower, shorter and overstuffed to be a 10F
Email me if you are interested: melissaaspencer at hotmail.