Herbert Watson Thomaswas a stock car racer who was one of NASCAR's most successful drivers in the 1950s... (wikipedia)
Sirens are not a good option, especially with our topography.
What's very important is that we are all on the same page and that it's documented.
There's a lot of reasons not to reinvent the wheel here.
It must be said that all entrants were extremely talented, and there were no losers at this event.