In offgrid locations as in any place of human habitation, effective disposal of human faecal matter and urine is a necessity for health, if not for aesthetic reasons. Composting toilet systems are one solution to this problem.. Be aware that local municipal authorities may have some regulatory powers over these kinds of installations, and there are some practical health limitations on disposal of the finished product (composted humanure). Processing of urine requires careful consideration, but disposal and beneficial use in the manufacture of garden fertiliser (and black powder ) are also factors to consider
Arizona ADEQ has two systems that they would approve of. A vent pipe and a clear bug catcher are part of it.
A simple humanure composting system. Guttering from roof collection could be plumbed to supply handwashing water. The structure itself could be used to support climbing plants to insulate the building in summer...a small power solar collector on the roof could supply lighting. Oh, and a Seers catalogue would be handy for entertaining the constipated when they are 'laying cable'