This is another key, split the day in half, make a race schedule for the entire year, flip flopping the little guys with the big guys, so everybody knows what time they have to be at the track, if you want to show up at 7 and stay the whole day you can. If your race is late afternoon, you know you can show up at 1.
I imagine I am in the minority, but I have a son that races 65 and I am racing as well. I am not doing a Saturday race for the boy and then coming back on Sunday for me. Won't happen, we will just race the boy.
Race order is also key. Nothing like running the D11 fair races and having the 50 and 65 kids go after both 250 and 450 classes with no track prep! Those ruts swallowed the little bikes. Tough to work on basic corning skills when they ride around the outside of every corner to avoid the 12" deeps ruts!