These are some examples of simple buildings. Often used for storage, livestock, and work spaces. The shed, lean-to, monopitch style of roof has the appeal of reducing material cost and labor required to put up a structure. I like this aesthetic for the mountain.
In my research I found that urine on its own is generally sanitary, and a great fertilizer when diluted. Solid human waste requires more careful handling to ensure harmful bacteria are discouraged; by keeping it dry, odors are mitigated. Dry toilets and composting toilets are managed differently but both start with a toilet. The smallest designs use buckets and a special toilet bowl.