Actually I might have a suggestion. Have you tried any Cannondale XS size shorts? They seem super tiny. At least comparatively. I tried to try the Cannondales on when I saw them on sale. They about fit my calf. But I don't know how the leg-waist ratio is on them.

I'd say if Nike made bike shorts you'd be set - I love their running tights, except that the legs are always super tiny and the waist is usually large, so they pull themselves down.