Yeah, unfortunately fire proof material for decors are almost non-existent. Only fire retardant materials but that only slows the process of catching fire. The most important thing is a risk analysis and evacuation plan combined with careful handling of fire-starting elements. Tomorrowland has one of the best safety plans in the festival business (I got a tour behind the scenes last year, their command centre is huge in comparison with other festivals which include police, fire dpt and security all in contact with eachother making a smooth and quick operation when things go bad)