For skirts and dresses, I actually recommend going at least knee-length. Then you can sit cross-legged on the ground and not flash anyone or end up sitting with nothing underneath you. Plus they're better for dancing and catching breezes.
This made me laugh out loud. Last year during Cat Power's set, I was overly concerned with people being able to see my underwear when I noticed a couple of young women in front of me who were wearing COMPLETELY SHEER BRAS and nothing else. Figured no one would be interested in my underwear with them around. ;D
On the subject of making clothes for 'Roo, I noticed JoAnn's was selling bolts of fabric with smocking on top and then just plain fabric. You could simply seam and hem it for a simple sundress, or find coordinating fabric and do alternating large ruffles/tiers for a maxi dress.
I'll be wearing yoga and bike shorts under my skirts and dresses so I'm not worried about flashing. I like to jump and do cartwheels and one-legged hooping and I learned as a child that shorts under skirts is the best idea ever.
As for making clothes, it's funny you should mention the smocked fabric, Sassbox. I bought a short one from Joanne's; it's pink with a gradiant rainbow color all the way down. As a dress on my 4'11" tall self, the hem comes to about 2 inches past my butt, so supershort dress but can be worn as a skirt as well! I love double-duty clothing.
I'll post photos of the stuff I've made and am about to make once it's all done. :-)