The problem is that warm lights just look dimmer than they are in reality, you need objectively much brighter warm light to see anything at all. 505nm is a comm

The problem is that warm lights just look dimmer than they are in reality, you need objectively much brighter warm light to see anything at all. 505nm is a commonly available wavelength that is very near the eye's peak sensitivity in the dark, so a very low powered light would provide sufficient light, and it wouldn't be more overstimulating than moonlight unless it's way too bright. The only drawback it seems to have is that it's rather close to the O-III astronomical filter, I don't know how much it matters.