Give each movement a place
Mark guest arrival, food or activity areas and the proposed facilities. Ask the organiser to review the route to toilets and washing alongside the vehicle approach. An apparently convenient corner may be unsuitable if it becomes the main unloading point or queue area.
Include the people who finish last
Cleanup teams can need facilities after the advertised event ends. Explain that period and the availability of permanent bathrooms. Confirm the pickup request and a contact who can admit the supplier later rather than treating guest departure as the collection appointment.