If they do not have a mandatory pit stop, why would anyone do driver change. I know it is a just for fun, but still should be atleast competitive. I have done hour enduros in the past where they made a 5 min mandatory pit stop, so if cars wanted to changes drivers they could and still have a chance in the event. The pit stop could be made a anytime. If they are not going to do it to help driver changes, it does not make much sense to run it