Is it possible to host 2 different length races? I have changed the player.json for number of races but there isn't an option for race length that I can find.
You can change next race length in-game in admin menu in top left corner. I suggest to not use option for number of races. You can just press restart warmup in voting menu after race one is finished. During warmup go to admin menu and set next race length and this will be enough.