QF,
I am not 100% following you, but, if you are asking
me; "Where did you get that 30' and under info from?"
..then I can say, I see it, HERE, 12A and 12B . I read 12A-B to mean
that if I have no trailer, and my truck is under 30' long, I do not need
an AMBER on the SIDE at the front.
So...