Slow-moving vehicle emblems shall be displayed on the rear of the power unit. When a combination of vehicles is being operated in a manner that obscures the emblem mounted on the power unit, an additional emblem shall be displayed on the rear of the rearmost vehicle in the combination. [1983 c.338 §469; 2001 c.529 §5; 2007 c.70 §347; 2007 c.207 §3; 2011 c.360 §19]