I think the moody atmo and lighting are nearly perfect. Maybe, if possible, try to lower the sun a little bit and increase red decay to give the light a slightly more orange color. That would look pretty cool on the snow I think. The clear sky fits the scene perfectly, I wouldn't change that at all.
As you said the clouds could use some work, maybe a little less color roughness of the color...can't say for sure, I'm not so good at cloud settings

I really like the image, looks very good! Look forward to see the final result.
Martin