Hi, welcome to the forum! Glad you joined!
What are the dimensions of that long storage tub? A photo of how it is set up could be really helpful.
Ducks and chickens are different species with different requirements. Ducks need to clean their nares and keep them moist to help prevent infections so they need deeper water. Chickens do not. The ducks can make a wet mess with that water.
Some people are successful raising chicks and ducklings together but it doesn't sound like you have the facilities for that. Keeping them separate may be your best bet.
Are you aware that a male duck's private parts are built like a corkscrew. When chickens mate they just touch vents. Ducks are built differently so they can mate while swimming in water. Many people keep ducks and chickens together without issues from this but if a male duck tries to mate a female chicken he can severely injure her. This does not happen often but there are a few threads on here where it has.