I throw the blanket over my deck railing and one of those soap mixer nozzles from harbor freight. I douse the whole thing in orvus and whatever that enzyme pet wash carpet shampoo, let sit, then rinse with the pressure washer on low. If one is really nasty I will fill a trash can with water and they enzyme cleaner and let it sit for an hour before doing the usual process.
They come pretty clean and don’t smell bad, but when I build my barn I am adding commercial power so I can have a commercial washer.