sleep display on imac in console mode

I'm attempting to run a flaky imac (running 10.8.5) as just an ssh server, headless and without the GUI running.

I've made this work by disabling the com.apple.loginwindow.plist and com.apple.WindowServer.plist and enabled com.apple.getty.plist and adjusting /etc/ttys to run a console with

console         "/usr/libexec/getty std.57600"  vt100   on secure

This is fine. No GUI, I can ssh in just fine and if I have a keyboard attached I can log in on the console.

However, even with a pmset -a displaysleep 1 the display never goes to sleep. I'd like it to be asleep all the time, as I've got the iMac under a desk and only intend to use it over ssh.

Is this possible and I'm just missing a step or am I out of luck?

Update: My notes on how I got it almost working.

Mac OS X's idle time measurements require a Graphical User Interface (GUI) to provide the "user inactivity" measure.

Without this measure, the operating system can not determine if the Mac is unused long enough to sleep the display.

Disabling the WindowServer will restrict most of OS X's unique features. Have you considered booting to a headless Linux or other operating system?