Looks like your working hard on creating quality skies Bourne. If I may suggest...in pics #2,4 and 5 your cumulus layer forms a hard horizontal line. Try to extend the bottoms down a bit or spread then  raise the cumulus layer. Example..if your cumulus now is from 3,000 to 4,000 ft, raise your tops to maybe 7 or 8,000 leaving the bottom where it is. Then experiment with moving the entire cumulus layer up and down in elevation. They can look very realistic if they're spread out more with less sharp or definitive lines. They shouldn't look like"pieces" of clouds. I hope this helps a bit...