I think the Rio line is still around. At least it has not sold out if they stopped making it. Just say several on flea bay. I have the old Rio lazy sink intermediate sinking line and it's light blue. I see it fine. One of my favorite lines. I have three different white Trevor Morgan fly lines and don't really have trouble seeing them in the air either. They might not be as easy as optic orange to see but they are far from impossible to see. I almost forgot, I have several really light colored SA lines. I have a really light blue Tarpon taper, a bonefish taper that is almost white with a hint of tan and a really old white Bass line I forget who made it. I have never really had a problem seeing them in the air.
I also have several orange to optic orange lines that I don't really think cause problems either. My Pike lines are Orange and it's a color Pike see so you would think lining them with it might not be good, but I have never seen any evidence that it is a bad thing to line them with it. But that's Pike. Maybe trout might not enjoy being lined with a bright orange line.
I have a camera case that is good to 330' deep and scuba gear so next summer I think I will try a couple of experiments with low angle shots and lines against the sky etc. Being in complete control of the experiments and with proper editing I'm sure I can make me look right.