Two years ago, we made our annual trip to Yosemite at Thanksgiving. We had our site booked and arrived around 3:00pm with our daughters and their two trailers. Sure enough, someone is in our site with a rental motor home and they're gone. For anyone who knows Upper Pines Campground, there is really nowhere to park and wait for someone to return without driving over to Curry Village.
We checked around for the owner without any luck. I spoke to the campground host who told us to wait until they return. We had a coach full of equipment to set up for our week long stay and we were about 1.5 hours before dark and a quick drop in temperature. I told the host that was unacceptable. Someone's lack of consideration is not my problem. I asked the host to call a Ranger. A Ranger arrived within a few minutes and checked my paperwork. To my surprise, he called a tow truck. I figured they wouldn't have the courage to do so, but he did. Apparently, that was the third RV that day that they had towed out of a site. I felt bad, but it wasn't my problem.
About two hours later a lady and her daughter came walking into the campsite. They had a puzzled look. I asked if they were the ones in the site with the rented motor home. She said yes. I explained that check out was several hours ago and her coach was towed to Ysemite Village. She queitly walked off.
Again, I felt bad, but we've been camping for over forty years. We've never stayed past check out time as we feel it;s rude and inconsiderate since I'm paying for the site while someone else is enjoying.
IN this case, the OP placed his slip on the post and most likely someone removed it. The host didn't need to be involved, other than beng a witness, since the host new he was there first. He should have called a Ranger. It's nice he took the "high road", but I don't reward cheats or inconsiderate people.