I think anything absorbent works. I've used hobbit trail (is that the brand?) wood shavings for gerbil/hamster cages, too.

As others have said, I've got a 5-gallon bucket with a commode seat and lid on it. I put a couple of trash-compacter plastic bags in it. Put a little litter or wood shavings in it, then add more after every use. My set up pretty much seals the unit when the lid is down, so odors are kept to a minimum. Solid waste only.

If you're out of water, when there is no water in your bathroom, line the commode with plastic bags (I think trash compacter bags are sturdier, and I prefer no breaks or leaks), and use that.

When you've filled up a bag, our local Red Cross volunteer suggests burying the bag in a shallow hole in your yard where you won't step on it, adding bags as weeks go by, till sanitation starts again, then asking your garbage company how they want to handle that particular pick-up.

In your experiment, what did you plan on doing with the bag o' droppings?