Our member Zerbu has found a way how to set Club Gatherings and Hangouts that are introduced with The Sims 4 Get Together in Granite Falls, a vacation world that came with The Sims 4 Outdoor Retreat.
It was mentioned by at least one guru in interviews (I heard it in more than one interview, but I don’t remember if it was the same guru) that you couldn’t have club gatherings in Granite Falls. Since the team is big, it’s possible that the entire team wasn’t aware of everything, because it turns out you actually can, and it’s not even buggy.
You can’t have club gatherings at Rental or National Park lots, but if you change any lot in Granite Falls to another type (Gym, Bar, Spa, or whatever else you want), you can not only have a club gathering, but also set it as a hangout.
It doesn’t appear to be a mistake, because the game is properly set up for it. If you set your club hangout to a lot in Granite Falls and attempt to start a gathering in a normal world, you won’t receive the option to travel for free. The same is true if you have a club hangout in a normal world and attempt to start a club gathering in Granite Falls. You will receive the option if you are in Granite Falls and have your hangout there.
So, looks like your camping groups are perfectly possible to create.