I've read that you can knock about 2hrs off the required time to induce a flowering response by irradiating with fairly intense far red (>700nm) light..
Incandescents produce more far-red than red, so you could probably push the equilibrium and speed up the dark cycle requirements by illuminating with incandescents for a few minutes just prior to lights off..
Or, for the ultra-rich, get something like this, but bigger:
http://www.asahi-spectra.com/opticalfilters/syousaik2_ver2.asp?key=ZBPA730
And use it to filter incandescent light through the entire day (light and dark) when you want the plants to flower.. That could reduce the dark requirement tremendously, but the filter would cost thousands..
Moonlight carries a large proportion of far-red radiation, and its been found that moonlight can enhance flowering response of short-day plants..