We could try to run 4 at a time, we would probably have to generate our own round robin table and keep the scores by “hand” — I have used their software before and I’m pretty sure it does not have a round robin option. With 8 guys; four racing at a time 5 min heats with 2 min between each heat, the entire race will take 2:00 hours; if go for 10 min heats that climbs to 3:20 hours.
We would probably have to rent the entire track for 3 hours on a Sunday.
BTW, we probably need 3 marshals at all times.