… became so much easier since Skylum recently introduced Luminar 4. I didn’t use their skies (not suitable for big blow-ups) but used my own skies (saved in TIFF). The first picture is the original (as shot) and the rest are all with different skies. And in Luminar 4 there is a slider with which you can adjust the coloring of the rest of the picture so it matches (more or less) the sky. Not one hundred percent perfect but the beginning is there. The photoshop plugin also has easy to work with modules for portrait- and lanscape photography.
Slide show (5 pictures: Less is more)