I can always give them a hint in that direction. Might be a good idea.
After some initial mishaps (not fitting images, probably a small mistake somewhere again), I managed to get it working. Saved the 'individual panorama PTGUI project' for final renders. Lined the individuals up in PS and it worked flawlessly! Terrific! Two bigger tests are now rendering (4200x2527), see what they do...
As I have to fill about 80m of wall, I have to go round twice, with two different terrain bases or it will be too much the same. I have to figure out a way to fit those two together, although a small change is not too bad, there's a gap in the wall there anyway.