Here is a BYC post regarding sulphur:
https://www.backyardchickens.com/th...you-are-experiencing-this-please-read.830897/
Treating depluming mite:
https://zenodo.org/record/2178293/files/article.pdf
Using ivermectin for depluming mites:
https://www.backyardchickens.com/threads/depluming-mites-and-elector-psp-help.1456762/
The difference between regular mites and depluming is that they burrow into the feather shaft - like human scabies and need more than just permethrin to treat.
In the past, I have added powdered sulphur to my dust baths for chickens just for an extra prevention. I've not treated ducks for depluming mites, but have used ivermectin. While there is an egg withdrawal and you shouldn't feed the eggs back, some do eat the eggs. You can find posts here on BYC regarding that.
If your ducks have a respiratory issue or you are afraid they would ingest the sulfur, then I would go the ivermectin route. As well, if you are dipping them, I would make sure that they could not drink the sulphur mixture. As a side note, I just looked up the sulfur lime, it looks like it's a premade product. Although it is useful on some animals, not sure about chickens, so definitely use with caution.
I think when I read about dipping the chickens in a sulphur bath, you used warm water, a few drops of soap, and the sulphur. Keep their head from getting in the water, let them soak, and then let them dry off - this would be done on a warm day. Of course chickens don't like to preen while they are wet, but we know ducks do! Maybe another solution would be to dry them with a hair dryer on low if you go the dipping route.
Whatever you choose to do - good luck!