+1 for dropoff marking, as soon as you’re above just a couple of mates anyway.
Number involved… Just like pushirons the bigger it is the more cumbersome it gets. Mine got up to IIRC 70 people on the road at one point, which is a hell of a lot and means you need to put some serious legwork into it- finding suitable places to stop, even to eat, not to mention that the more people you have the more likely it is one of them bins it. I basically planned for 1 minor crash and 1 breakdown.
It’s not brain surgery really but mate’s rides are a bit different to open rides usually.
Oh yeah- and you need at least one other person to be totally clued up on what’s happening. I always lead from the back 😉 Get some fast reliable person up the front to waymark, I sweep so I know when people have hit problems, but even then you really want to have someone else who can deal with issues too- I had to stop for a crash almost immediately in the first year of doing the big rideout, and it seriously bumped the timetable as there was nobody left rolling up markers etc.