Look around 20.523048 -87.192555 on Google Earth. Image date last I looked is March 2010. I have never counted how many there are. Some are new and some are old. Most RVs have palapa roofs. Beneath those roofs in some cases they have built houses around RVs. We saw some with concrete walls and RVs up on jacks with no tires or wheels. Some of these do come and go but for the most part they are left onsite year-round. Owners fly in and out of Cancun. These RVs never go anywhere and haven't for many years. In many cases the permits expired a long time ago. If you zoom in close enough there are a few RVs that never got around to building palapas but there are also some spaces reserved for transients. When we visit around Christmas back more than a few years ago the rate for a space was $6,000US per year. I have never taken time to count how many of these there are. I have no idea what the laws are or how this place gets to do this. They have a restaurant and dive shop. We know of many places with "extended stay" RV parking in various parts of Mexico mainland other than Baja - but none quite like this one.