Well, I got caught short at PF a little while ago, no public toilet and a very demanding bowel movement wanting to move.
Behind some hangars were a few garbage skips, and in one skip was a pizza box and some newspaper. Crouch down between the skips. Wrapped the boxed result in newspaper, deposited it in one of the skips. In the sun. several days before pickup was due.
Luckily I was on my way shortly after.