Yes, ADA restroom trailers exist, and a public festival VIP area that is part of the event usually needs at least one accessible restroom option that meets 2010 ADA Standards, not just a wider stall.
A compliant ADA unit style restroom trailer is built around wheelchair access: a clear turning space (the Standards call for a 60-inch diameter circle or an equivalent T-turn), grab bars at the toilet, an accessible route into the unit (often a ramp if the floor is raised), door clear width, and an accessible sink. A four-stall trailer with only standard-width stalls will not satisfy a permit review that asks for ADA compliance.
For a three-day outdoor festival with alcohol and about 200 VIPs per day, the city is asking the right question. If the VIP restrooms are the only flush facilities for that area and the event is open to the public or ticketed as a public assembly, expect them to want a true accessible stall in the trailer mix, or a separate ADA portable toilet on the same accessible path. Leveling the grass pad and running a generator covers placement and power. It does not replace the clearances and grab bars.
Ask the rental office for the trailer's accessibility cut sheet (turning radius, ramp slope, grab bar layout) before you lock the permit language. That paperwork is what inspectors check.
