The farm I work at has two rolling double sinks with a lot of space on the side of each - I believe it's originally restaurant stuff, but we can fit two crates of produce on each side. They have a normal faucet and a spraying attachment (I'm led to believe it's called a flush valve but I could be wrong) that can be attached to the garden hose, but we also often just fill the sinks. Usually we just let the sinks empty onto the paving and flow into the flowerbeds, sometimes we put buckets under if there's soap or anything involved. In yacon season we pull a lot of deeply muddy tubers out of the ground so then we roll a sink into the garden proper and attach it to the hose there so we can spray them down asap.
We also have a big basin with a grate over it and a hose so we can spray down large things roughly, like muddy crates or things like carrots or beets that don't need to be 100% clean. That basin is directly connected to our pond so it's good for things with a lot of sediment.
No specific tips except for the lever that's already been mentioned, but hope this helps anyway!
