That is very similar to how i fast... drinking only within a small window each day and resisting mild thirst over the remainder of the hours. Without looking back for the specifics, i believe i averaged fasting dry for about 18-20 hours each day in the past 3 fasts. Hey good point about not having to get up in the middle of the night to pee, i hadn't even considered that positive aspect ;).
There is very little information that i have been able to find on dry fasting, but what i have seen and what i believe through personal experience is that the awesome cleansing and healing we experience in a water-only fast is intensified even further in the periods we are not drinking.