Its a cool idea. My brother does this with Rockets and Astronomy get togethers. They camp, suck down suds etc. The problem they have had is getting a community to allow for it. Private camping grounds they couldnt do, liability reasons. They did that several times and it just didnt work based on rules. Astronomy is at night, campgrounds wanted everyone in bed, silent, by 1AM. And obviously Rocketry doesnt fly LOL in as far as launching them.

Loudness, booze, that was that. The camp places didnt want liability.

So I guess it took a little while but they managed to find an area in the desert basically where the country granted them access within reason and they came to terms on rules. Liability waived unto the group itself. With the Rockets, obviously they need inform times/dates etc as airspace needs to be clear. Astronomy has went well I guess.

They do it freely for "club members". If you charge any form of admissions things get a bit more hairy as now its construed public event which means insurance etc. comes into play and it varies by state. Even without admissions can be construed public event, really depends on the state. Some are really lax, like here where I am, not so at all.

With things such as get togethers at seminars and such in buildings, the building management does all the fine print stuff. Like hotels do when there are conferences. The moment admissions are charged (in as far as I recall) its considered a commercial gathering although if a not for profit entity is established then can go that way under whatall form of NFP like 501c etc.