I provided food and water 24/7 for my ducklings. I don’t have large ducks. Being a softie I wanted to keep doing it after I moved them outside, but cleaning the soggy coop daily got old after a few weeks - even with building a drainage system. I think they stayed up all night flinging that water everywhere!
For the last 2 years my vets have had me have my ducks on a 10 hour daylight schedule year around to reduce reproductive activity, because one was very ill. So they have a blacked out room in the barn with a light on a timer. We put them in the barn right before 5:30 pm and let them out about 7:30 am all year. They get no food or water all night. My vets have told me it is fine for them to not have water all night as long as they have access to it all day. And that they shouldn't be able to get their bedding wet, so if I wanted to give them water at night I would need to build a separate area for them to drink.
Before we needed to have the 10 hour daylight schedule we put them to bed about dusk, and let them out about 7am.
After you move your ducklings outside I see nothing wrong with putting them to bed early for your own sleep needs/sanity. The emotional health of ducks is very important to me. It's just, you'll be able to be a better duck owner if you get enough rest.