I have hiked, backpacked and even x-country skied in my long heavy twill skirts (Banana Republic from about 30 years ago). I wear long thick socks/stockings if I am in hiking boots or on skis, otherwise I use hiking sandals. Skirts hike up easily for crossing water and most importantly, they make it easy and modest to pee! The airflow is nice too on a hot day and they are far less gross to put on dirty when on a long hike or trip. It would be fairly easy to make one, they are "A-line" with a zipper, made out of a heavy "military" cotton twill (On mine, the side pockets are trimmed with leather so they don't fray).