I am pretty new to ducks, but I have had no problems so far with leaving mine without water overnight. I currently have 3 adult ducks which sleep in a dog crate at night with food but no water and they've slept that way since they were about a month old with no issues. I also have 7 babies right now that are various ages and they sleep in a crate in the chicken coop at night with no food or water.
I tried putting water in with the babies in the coop, but they would without fail slosh it all out into the shavings of the coop. After cleaning up shavings that were soaked, stinky, and teeming with maggots at one point (EWWWWW! but the chickens LOVED it) I decided the ducklings could sleep without water. Figured it wasn't like they were drinking much anyway since they usually had all of the water dumped out within 5 minutes.
I like the idea of having a duck brooder with a 'drinking veranda', though. I might build something of this sort for future batches of ducklings. Maybe a solid-floored brooder with a section of wire floor where I could put the waterers and let the mess fall through...or maybe just a wire-floored brooder with a smaller sleeping spot with a solid floor. Hmmm....