Long story short I think cloud opacity at 0.7 would be a good default setting.

I initially found the clouds at default settings made it almost impossible to see anything until they went away, and also didn't really add to the dark atmosphere. They just block your view regardless of light level.

I tried reducing the cloud transparency to 0.6 in the startup settings and it fixed the problem but I noticed it didn't really feel like a planet of night anymore, not like it did. I tried 0.8 and that still greatly improved visibility and seemed quite playable even after I removed my light amps.

Since many players probably want/need better visibility then I do, I played with 0.7 no light amp for a while. It's perfect. Very gloomy and I forgot about how the clouds are rendered incorrectly and just felt the gloom. Visibility is great if you get some lamps and pretty poor when you don't.

I recommend further reducing the effectiveness of light amps also. It looks like they're around 90-95% effective and I'd reduce them to around 30% effective. Give people a reason to put lights all over their base.