A vehicle sign may be displayed only when all of the following conditions are met:
A. Signs must be painted on or applied directly to the vehicle and may not extend beyond the horizontal or vertical profile of the vehicle.
B. Signs shall not be mounted in the bed of a truck.
C. The vehicle displaying the sign must be operable, registered, licensed, and driven at least once a week.
D. The vehicle displaying the sign must be parked in a legal parking space.