I believe the hardest parts for this type of event will be A) Location/ Venue. This is why we need to be permitted for a large open area, so we run into no legal issues or problems. And B) setting a good time/date for the meet where weather and everything will be nice for all to enjoy. It will need to be far enough off for adequate prepping, time to get days off for work, all the normal life shenanigans. But also not so far off that it generates no interests until the weeks before it begins. Also, C) we will need to "market" the event, to generate tons of interest in all the different OL groups. If we truly desire a turn-out of overlanders to rival all events on earth, we HAVE to reach them all--or as many as we can.
I too agree that a small fee might be required, to help with venue fees and everything. We can accepts volunteers to help with end of event cleanup--the idea is to leave no trace but tire tacks--and we won't need extra $$ for cleanup crews. Food, drinks, fuel, all essentials will be up to the overlanders to bring--its kind of the point anyway to meet at a location for a massive campout! Its nobodies intentions to have to pay to feed each other--were all adults capable of feeding ourselves! That being said, however, I wouldn't be objective to putting in a few extra bucks for a last day feast, where we roast a couple pigs or something and collectively eat and each share little something about ourselves that nobody else in the group knows.
It is doable. WE just have to do it....