Don't all county fairs in Iowa have open classes? I can't remember anymore,but used to be able to get a list from somewhere. I know Jefferson, Lamoni, and Colfax used to have open shows. Hell, I can remember years ago we use to travel to Iowa for open jackpot steer shows throughout the summer,they were all night shows,back in the day.
Dont know where you are in IA we are about an hour south of the IA line and will have an open show in Shelbina,MO on July 8th think cattle in place by 4 and show starts at 6 usually done by 10 most of the time will have 100 head