Consider buying a tent, turn it upside down in a little pit to get cleaner soil. Put a rock at it's middle & cut the ground sheet on three sides. Make holes in it to stretch it out with guylines for a roof & sleep under it. Hold the corners down with the other lines. Collect rain & not water from polluted streams. Use Nylon poles not Aluminium. Dig under your cover. Do it under a tree.
If it snows get into it & collect snow from the pit to eat.