October 2026 farm wedding: 80 guests, 4 hours. ADA unit needed?

We're planning an October 2026 wedding on my family's farm, 80 guests, ceremony and reception under a tent, about 4 hours total. There's no indoor plumbing, so we're renting portable toilets. The ground is grassy and level, and a truck can reach the spot fine. We'll have alcohol and catering.

I know we need at least a couple of standard units, but I'm unsure about the ADA requirements. Does the ADA 5 percent cluster rule apply for a group this small? If we rent three standard units, do we still need an ADA-compliant one? What's typical for a wedding this size?