im not a fan of this 'heats to be run in clockwise and anticlockwise directions'.. why would you do that?
You need to maintain consistancy on the day, all races need to be run in the one direction. Anyone who is half serious about thier racing will develop a setup for a track as the day goes along, to change the racing direction in the middle of a race day is not a very good idea and will only make people not want to come back to the track and race.