Some years ago I severely injured my back and could not access the bathroom, which was on another floor.
I took one of those lightweight home hospital potties, put a plastic bag into the bucket part, and put a bag of loose pine sawdust kitty litter next to it.
You use the bucket, sprinkle a cup of loose pine litter over it, no smell, no problem. And I do mean no smell. I had to sit right next to it for weeks.
Do not use standard clay kitty litter, which is made of bentonite clay. Yes, it will work, though not as well with the odor.
The problem is that bentonite clay is very durable. While it absorbs pee well, it does not want to dissolve, it wants to clump up and stay that way. This is fine in a litter box but not when you want to biodegrade the mess in a hole in the ground. The clay will not mingle with the dirt. It will encapsulate the pee and the poo.
The loose pine type of litter absorbs moisture very well, and biodegrades easily. It is also acidic. I don’t know what that does to the bacteria in feces, but bacteria generally don’t like acidic environments.
If you run out of pine litter, you can use sawdust. Do not get the pelleted pine litter, it will not work. It will stick on the poo like sprinkles on a cupcake.
On a separate note, you may want to keep the pee and poo separate, with a potty for each, and some water in the pee pot. The pee is not only fairly harmless, but if mixed with ten parts water to one part pee, it is a good source of nitrogen for your garden, and will not burn the plants. Doing this also greatly reduces the total bulk of what you need to dispose of.
I have a question: Has anyone tried taking the poo and simply tossing it into a hot outdoor fire? I presume it would be a bit smoky, being damp, but it seems like burning the poo would totally get rid of the disease risk, contamination, and disposal problem, leaving only sterile ashes which could also be spread on the garden.
I did look this up in the past, but could only find references to it being done along with a lot of other types of garbage, which caused chemical pollution problems. This would not happen if it is burned by itself.
Best wishes JW from NY