*Can anyone - or has anyone already - made Bryce Skies like this?*

I'm sure it can be done in Bryce.  I'm not sure it can be achieved in the sky lab only though.  I did some experimenting and came up with this.  This is a custom sky with all clouds turned off.  The clouds are "fuzzy cloud" preset mat that I added two more channels in mat lab and tweaked in DTE.  then applied to six separate cubes in the scene. 

The result would make a presentable stratus.  The next step would be to add the cumulus clouds at a lower altitude and get their color layers right.  With work it could be done.  The render times would be unbelievably long.