We have large groups, (20+) and usually max out a Rogue permit and could bring more. Multiple families = almost 1/2 of the trip are kids, (6-14).
All trip expenses except alcohol are split per person.
Whatever it takes to make the trip happen = trip expense. Shuttles, permits, boat rentals, food, etc. Everyone is responsible for getting themselves there. There are no discounts for being a kid or penalties for not having your own raft.
An approximate deposit is due a month ahead of time for working capital, (buying food). One person plans/purchases food. All the adults used to be guides so it's not that hard. The banker keeps track of the total and bankroles the rest. Within a week or so post trip and after everything is totaled people either pay the banker or get a refund.
For us, it's about being on the river with my best friends and our kids. This is the easiest for us. We try and keep the nickel and dimeing to a minimum.