The good news is ducks arent picky or need anything fancy. A properly ventilated plain box that shelters them from the wind and rain and predators is good enough. They dont roost, they dont need nesting boxes. Just a boring roof, floor, and four walls makes them happy, its a pretty easy build...
Once you get down to bare dirt and you know you cant try to re-grow the grass, you can toss grass or leaves in as a layer that you just scoop out and discard when they get mucky (or leave and let compost under a new layer in the same deep litter sense)
But as another poster indicated, it doesnt...
So, your space is pretty small. A common recommendation is 4sqft PER bird for their coop and bigger for their pen, even if they get free yard time.
When you've got a bigger area, keeping their litter clean becomes easier because theyve got more space to spread out and not soak it so badly, you...