I used to just dig a trench when backpacking...
My first year of summer camp in boyscouts as a kid I refused to use the kybo (glorified deep hole in the ground) more because of all of the bugs crawling around the thing. By Thursday of my first week, nature was pressing its needs and I was faced with the decision of either getting over my fears or finding some other alternative. Well, the camp was busy so finding a quiet spot was just about impossible, so I gave in and used the kybo. At least it had walls and stalls (without doors). When I went to Philmont a few years later, the kybos were literally a box sitting out in the woods that had two toilet seats on them--back-to-back. We used to call them "copilot to bombadier" kybos.
