Has a CD of a GS meet and co-CD of a jet meet. We always open the field the day before to let people test fly there planes. This has always worked well for us. Also we call the meet at 5pm so the pilots can fly anything they want for the rest of the day. This also lets the pit crews time to relax. If at the time some one wants to test fly a plane, we close the flight line and announce the test flight.
Only once in all my years have I had one person fly a new plane during the event hours. How did i know? He was chasing it down the runway trying to get it under control. I had to go out on the runway and tell him to land or crash, but get the plane down NOW. We did have a talk about that and he said he was sorry and we both had a good time for the rest of the meet.
A side note, all the test flight we has allowed have always gone well. That is testament to good pilots and their set-ups. Dennis