Your Venue has an Outhouse
Okay, it wasn’t an outhouse, but a Port-A-Potty.
Being in NE Ohio, I DJ many weddings at barns; some of them don’t have bathrooms! Yes, this is rare, but you should double check.
A good bathroom provides many benefits to your guests. They’ll have a place to freshen up and make sure they look great. Some might get sick from drinking too much; having a dedicated stall in helpful. Parents may need an area to change their child’s diapers. And you can put a nice basket of breath mints and Aspirin for the guests.
Providing guests a small Port-A-Potty simply isn’t the right way to go. It’s small, not temperature controlled, smelly, and often dark once the sun goes down. There are vehicles that provide nice portable bathrooms. These are bigger, offer power, and are sometimes temperature controlled.