trailer marker lights

[Scrounger]

I have another thread on trailer LEDs but this is more of a nation law question. A web search has found nothing. Do all marker lights on the side of a trailer have to be yellow other than the combination tail lights which have a red side marker.

I have a 16' trailer and I wanted to put another red marker light towards the back of the trailer, within two feet of the end, to better mark the trailer. I've put two yellow lights before the tandems.

 

[Scooby074]

This page should help. Trailer Poster Table for Website
At a quick glance it appears you can have a secondary red light if your more than 80" wide and have something sticking out from the side like wheels. Otherwise the red has to be "Each side at rear - as far back as practicable" It does appear you can have more than one light at that rear location though.