(1)    No person shall operate on a highway during hours of darkness any train of vehicles authorized by s. 348.08 (1) (d) unless there is mounted on each side of every vehicle in such train, including farm tractors and implements of husbandry, at least one lamp emitting a red or amber light visible from a distance of 500 feet to the side of the vehicle on which mounted or, in lieu thereof, at least one red or amber reflector visible from all distances within 500 feet to 50 feet of the side of the vehicle when directly in front of lawful upper beams of headlamps.

   (1m)   No person shall operate on a highway during hours of darkness any train of vehicles authorized by s. 348.08 (1) (b) unless there is mounted on each side of every vehicle in such train at least one lamp emitting a red or amber light visible from a distance of 500 feet to the side of the vehicle on which mounted or, in lieu thereof, at least one red or amber reflector visible from all distances within 500 feet to 50 feet of the side of the vehicle when directly in front of lawful upper beams of headlamps.