Imagine if you did have the two classes in an endurance race, with no prize money for the doped up classes. Imagine in cycling if there was Lance and co doing the Tour we know and then another clean race, much like in Learning Mans with motor sport. Lance and co would be the LMP class.

As per motor sport it is obvious what class a car is in, there is no pretending to be the other class.

The testing would be more part of signing up to a given class, everyone would know what everyone was taking whether that be nothing or everything. Much like how in Motorsport you know cylinder count, oil used and so on.