The East Crawford Road covers a wide area and gives you more than enough space to set a new Showtime Road Rule. Also, you don't need to finish your Showtime on East Crawford Road, you only need to start it here.
Before you begin, make sure you set your tracker to "Best offline time" by pressing

. Now start the Showtime Road Rule event by pressing

+

. Keep pressing

to keep your momentum going and try to hit as many cars as possible. Most importantly you want to hit every bus you can find. This will give you an additional multiplier and makes this challenge a lot easier.