50-person film crew, 14-hour days: porta potty count?

We're filming a documentary on a rural farm for two weeks. The crew is 50 people, shooting 14-hour days with catered meals but no alcohol. Breaks are short and scattered, so a long line at the toilet would shut us down. The ground is level grass and a truck can drive right up to the spot. I'm looking at a mix of standard units and one ADA-compliant unit to meet the 5 percent rule, but I'm not sure if that's enough for this many people working this long. Should I consider a restroom trailer instead? How many total units do we actually need to keep things moving smoothly?