The latest play was also done in GIMP, so no PP3 or suchlike. It was effectively split toning using luminosity masks as the basic control.
The removal of the cables (which I did because I thought they were a distraction) was done with heal-selection tool in GIMP - part of the resynthesizer plug-in. Where the cables crossed the hills required work with the healing-brush tool.
I selected the cables by painting over them on a transparent layer using the pencil tool, then did a select-by-colour. On the original layer I was able to run the heal selection.