I also agree you are over thinking things. More often than not, our trips have been large groups. We've had at least 3 trips where we've had between 8 and 9 of us on the boat.

For provisioning, I email the group and ask if there are any requests and let everyone know what we are thinking for meals. We also provision online so I share the order and everyone is free to make requests/suggestions.

As far as helping out on the boat, as captain I let everyone know when help is needed and direct them. We've fortunately never had an issue with everyone pitching in for some task. That may be cooking, cleaning the dishes...etc. Everyone is usually very good at helping out.

Probably the biggest challenge is getting everyone there, but I always leave that up to everyone to do themselves and just give them guidelines on options of when and where they arrive.

And finally, I usually send out a rough itinerary so if there's any requests there they can get some input as well.

In over a dozen trips, this had worked very well for us.