A decent lean-to or debris hut can be constructed from downed deadwood and grasses or reeds. None of this is destructive or disturbing to the surrounding area. While a shelter made in this fashion might not last for decades, it will definitely do the job for a weekend, and rebuilding on the next trip is good practice (and fun if you enjoy doing it). You don't have to build a two room cabin to get out of the wind and/or rain. Get out, try it, and have some fun with it.

Troy