To hide your bottom, you could try a cycling skort. Here's one option:

http://www.teamestrogen.com/prodTY_1899.html

I have a pair each of the Terry Flare Skorts and Pro Racer Skorts. The Flares are stretchier and drape better, though I'm afraid of snagging them on something. The Pro Racers are made of stiffer fabric. While riding, I'm not bothered by the skirt portion of either one.