It is not a theory and it dates back to WW1 in design, and implemented in WW2 the most, and the M series of vehicles retained this because there was still a threat from the air and other types of attack, it also is used on tankers and the lot, It does not make sense to leave em out , but to be true they are the first things left behind in a real theater in most cases. If the wrecker is being used as a sweep vehicle it would never have the bows set up, and it IS a very very awesome thing for the hobbiest to do now and then, and it sure does keep it dry and ice fre also. but the design is and was simple the or all the targets in the convoy should look the same, as possible as to missdirect incoming fire. that is fact...randy