I thought it might be useful to have a list of all monitors (LCD or CRT) that support 15Khz.
On the LCD List, I have found one that works (sort of).
The Eizo FlexScan L565 will show an out of range message in the top right hand corner, but still displays the 15Khz image regardless. The other slight niggle is that the image for 15Khz will often overscan as the monitor's aspect ratio is 4:3. But as compromises go, I'm happy with it as an alternative to losing half my desk to a CRT.