"Arthur Morris wrote a post on the bird forum that
someone told him to change the colour temp in his camera to 9000 or
some such thing to get more color in sunset/sunrise pictures....
anyone ever tried that?"

Here's a little test to see if this matters or if it can be set in post processing.

First in the sequence is Auto WB
Second in the sequence is WB set to 9000K in camera
Third in the sequence is modifying the Auto WB image in RAW and matching the color temperature of image #2 as shown in Lightroom.