We have tried boost in the past. The more racers, the more of a disaster it becomes. If I know all the racers, boost low sometimes works. In general, people need to use caution on lap 1. I try to stress that when the race starts but people don't always listen. The goal is not to pass everyone on turn 1, it's to turn a double file start into a single file pack. You can use the draft to pass drivers later in the race.
As for the room emptying at 12:00, a bunch of my regulars are east-coasters like myself. I usually duck out around 11:45-12:00 and will pass the reigns over to who ever has been in the room the longest. Perhaps I should set it to auto start before I leave so the races continue w/o interruption.
As for tunes, I can share a few. After hosting this room for several weeks we have found it is best to find cars that are pretty close or a little over 450pp. Overloading a car with mods to hit 450 sometimes works but Lots of cars suffer from skinny tire syndrome...meaning they don't have as much grip as other cars. Two cars we know are very quick are the Lotus Elise and Honda/Acura NSX. Pull out one of those if your driving skills are putting you at the back of the pack. In the right hands though, they can be several seconds quicker per lap...which is why the veterans stay clear of them...not much of a challenge.