That's interesting. We met a group of caravanners recently crossing the Outback Track, ie WA to the East and one of them had put an ad somewhere and after all the communication between them, they all met at one town and continued the travelling. We camped with them a night around the campfire, a great group who wanted to meet new like minded friends. There were probably 15 off road vans, all of the same make. They intended to keep in touch. Had a friend who did tag-along tours. I guess it gets a bit involved when it's a business, insurance, etc.
We and a couple of others started a 4WD club in Canberra over 30 years ago (foundation President) which is still going with hundreds of members. There was a fair bit of work. We put out a magazine, newsletters, monthly meetings and did heaps of great family 4WDing and camping. Know of a group of retirees who just like to meet somewhere for a few days of bush camping. Too many people can sometimes restrict where you stop or camp.