December 2026 holiday market: 500 shoppers, 10 hours. Units?

I'm planning a December 2026 outdoor holiday market with about 500 shoppers over a 10-hour day. We'll have food vendors and hot drinks, but no alcohol. The ground is grass, and a vacuum truck can reach the placement area easily. I'm thinking about standard units for most guests, but I know cold weather can affect them. Should I consider deluxe units with flushing or a restroom trailer for better comfort in the cold? Also, how many ADA-compliant units do I need for this crowd? What's the best mix for a winter event like this?