I'm up for trying it Ferry but I think it may drive people away. Racing club tends to work well for short races. Armolli was long races and didn't really draw much of a crowd in I thought.
How about doing a feature and a sprint race like real GP2, say a 40 minute feature with pit stop and a 20 minute sprint race, or 30 and 15 minutes ?
Also Lee any chance of giving these a go round Portimao one week.