my enthusiasm level would drop very low for that trip if I had to do that orientation for 6 hours. I don't know what type of boat you are chartering or orienting people on, but that can make a big difference.

I have guests help me all the time, instruction takes minutes and it is pieced out during the week when you figure out who are the helpers and who are the sit and watch.

If they don't know each other just gather for a relaxing sail, you will learn and observe from their behavior who to instruct.