What about adding a NG+ Career category? It would make some annoying events like Professionals6 less frustrating, and overall gameplay faster for people that can't do long runs

Is there a way to clear the progress without clearing e.g. the cars?

You can press CTRL+LShift+X at the mission select screen after clearing the progress to have everything unlocked (every car with every upgrade in garage) without completing any mission

Soooo...?