Every wrecker shall display lettering on both sides of the vehicle in letters that contrast sharply in color with the background and are readily legible during daylight hours from 50 feet while said vehicle is stationary, and kept and maintained in a manner that retains such legibility, indicating the name or trade name of the wrecking service or owner thereof and the city and state in which said vehicle is customarily based. Such marking may consist of a removable device, if said device meets the identification and legibility requirements of this section.