Tolly,
Have you seen any paracord that has that "glow white" thread woven into a less dominately white cord?
All of the glow cords I have seen have been solid glow cord. But, it seems like they could just weave say 10% - 15% white glow thread in with kacki and brown tones that would look less blinding during the day and still functionally glow well at night.
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Yes, what you are wanting is called tracer cord. It is just a tad smaller in diameter than 550 and it is hard to find. I think I have some around here in a few different colors. Let me see what I can find around here later and I'll see if I can fix you up.