Just got back a week ago from 3 day. Opened at 9:00am closed at 8:30pm. Pirate Night it was open from 10:45 - 11:45pm.
Best time to ride was 6:30 pm - 8:30 pm. Kids would finish dinner and run and change their clothes and then ride the duck from 7:10 - 7:50 both nights. They got about 10 rides in each night. Then run and change clothes again and we would be at the show at about 8:05. Worked great!
We also thought we would do the same on Pirates Night but it was packed, they had a lot of issues that night as well.
I will say from experience that it is a different ride at night vs during the day. Both fun.