Keep the car numbers where they are currently located at all costs. If push comes to shove and moving the numbers is the only way, move them forward. Splitting the advertising space up is not only ugly, it limits the continuous canvas space for the sponsors to use. Numbers moved forward looks natural and gives the entire side of the car for sponsors to creatively advertise themselves. The number is the heart of the race teams, and diminishing it's importance will be a short sighted goal. If you ever want another iconic number like; 3, 24, 48, 43, 2, then you must make the number an iconic part of the look of each car. Making the number smaller or moving it in an unpopular and visually disturbing way could jeopardize the long term health of the sport.