The regulations you cited apply to regular taillights. There is no requirement for high mount brake
lights on trailers.
I think as long as you keep the originals, which meet the legal requirement, no one’s going to bother about additional
lighting, as long as the color and function are correct. Many folks have added similar
lighting, and I’ve yet to hear of a single person being bothered about it by a LEO.
Agree- this is a very sensible mod. There are a lot of tall vehicles on the road, and if you have to brake suddenly in close traffic, a truck behind you might not see the OEM lights come on, especially in bright daylight.
Personally, I think upgrading the OEM’s to brighter LED’s and adding just a brake light up high is all that’s really needed. An exception would be folks carrying bikes on the back that obscure the OEM lights. In that case a second pair of full function lights above the belly band might be warranted.
I’ve also put a strip of red-and-white DOT reflective tape across the entire bumper. I found it remarkably effective with traffic approaching from the rear at night. With the tape, lower is better, because it catches oncoming headlights sooner.