“Maybe it was added after this German took his trip?”
With only 2.5 meters of space there’s not a lot of room for even a small porta potty. Maybe a bucket.
Here it is - you only get a quick look at it. Yes, it is very small, but I imagine it could be a little composting head.
Given all the precautions they didn’t take, I guess they thought it was adequate for the numbers of people and periods of time they would be out there.
https://www.youtube.com/watch?v=ClkytJa0ghc&t=54s