I have spoken with a very elderly lady who hiked all across Scotland and the Lake District as a young woman, (she has never worn trousers, felt they weren't decent somehow, even if she insisted they were slacks) and she spoke of a *foul fire* that was lit to dispose of bodily wastes; sh1t was done on newspaper or the shiny Izal stuff and burnt, bandages, and rags as she referred to them, too, were burned as were food scraps. It was tacitly acknowledged among a mixed group of walkers that a foul fire wasn't for enjoyment, cooking or sitting around, but simply discrete disposal. The ashes of that fire were never scattered but buried. Sometimes the ordinary fire was used as a last minute tidy up when reddiing up to move on, and then it was declared foul, but mostly it was lit using embers from the main fire and kept downwind and a little bit away from the tents.
I know my girlfriends and I did this too when camping over thirty years ago. We burnt some bog myrtle, sweet cicily, mugwort or sweetgrass with it to sweeten the air a bit, but the fire was finished pretty quickly anyway.
Y'know those biodegradeable polybags? Like the poop ones for dogs, Do they burn safely? Do any plastics?
cheers,
Toddy