The idea came from something I had read about but to be honest I can't remember where I read it.
This group of 5 or 6 couples all went in on some land in different states and climates. They had one in the South, one in the Mid-west and one in the Rockies. Each piece of land was just big enough for 6 or 7 concrete pads (one for a caretaker). They let someone take care of the places in exchange for free camping. Then depending on the time of year, they each went their separate ways but they stayed in contact with each other so they could invite friends and such to use the camp sites not being used. They said that they rarely ever happened to be at the same place at one time. with the exception of the place in the South during the winter (I believe it was in Texas).
They said that while splitting the cost amongst them, it allowed them all to have several places instead of just one. These folks said that they got tired of having to deal with the upper end camping places (which is where they had met) and didn't care for what they found in the lower end either so they just made their own.