[Graham]

We get round these problems by classifying non-plastic chassis cars as 'Open Class', any plastic chassis with a pod as 'Pro-Stock' and all the one-piece unpodded chassis cars as 'Standard Class'.  Of course we still have the different eras but each era has these three sub-classes.

...we don't have problems with class domination and include everyone as there's a class for all.

That’s quite a good idea, as we are already running Class A - Standard cars, B - Modified class, Class C -ProCars, so we could have Class D - Metal chassis cars (B&W). We don’t allow ProCars in Event 1. So you have Class A, B & Class D cars in Event 1