Look at the whole event footprint
Identify where guests gather, eat and move between activities. Review which permanent restrooms are included in the venue arrangement and whether they remain open for your full event. Additional facilities should solve an actual access or capacity gap.
For public-space events, the city community-development event guidance is a useful starting point for approval questions. Ask the organiser or responsible authority about the current requirements for your setup.
Match the experience to the setting
Discuss standard units, accessible provision and any upgraded interior preferences. If a trailer is being considered, include its footprint, entrance and utility needs in the layout instead of treating it as a small cabin with different decor.
Place washing deliberately and consider how people reach it. Coordinate with the venue and other suppliers so restroom approaches do not become blocked by queues, tables or staging.
Plan the hours outside the invitation
Guest arrival and departure are only part of the equipment schedule. Delivery may need to fit a setup window, while collection can depend on venue access after the event. Both require agreement.
Describe the expected use pattern, any multi-day activity and the time between sessions. Ask how cleaning and replenishment are handled within the proposed arrangement rather than assuming the event booking covers them.