Originally Posted by cpaharley2008
I believe the smaller lights you refer to in the Escape 19 build are marker lights which are standard on the 19 and required due to it's length.
Wide-vehicle identification lights (the group of three in the middle) and clearance lights (on each side and separate from the tail lights; usually on top but not required to be there) are required on trailers wider than 2 metres or 80 inches. That means the 19-foot, 21-foot, and 5.0TA. While these are the longer trailers, it is the width - not the length - that leads to the requirement.
Anything beyond the basic set of left and right stop/turn/tail is not required by law and is an option or owner addition.