Winter 2026: will porta potties freeze solid on our open site?

We're breaking ground in January on a six-story apartment build in northern Wisconsin. The site's wide open, no windbreak, and the forecast says below zero at night. I've got 40 guys on site, 10 hours a day, six days a week, for the next 14 weeks. We're using standard units and one ADA-compliant unit, all on gravel. The truck can reach them fine. My last winter job, the deodorizer turned to slush and the seats iced over. The crew hated it. This time I'm thinking about deluxe units with sinks, but I've heard their fresh water tanks freeze faster. Will the standard units' holding tanks freeze solid if it stays cold? Should I push the rental company for brine in the tanks or switch to a different type?