I usually dust the roost bars with sulfur dust a couple of times a year, especially this time of year when the birds are confined due to weather. Some old timers use lime or permethrin for the same reason. Sulfur dust is cheap and easily found at any garden center, like Walmart or Lowes, and is specifically for mites of all kinds.
I wouldn't get too concerned with cleaning the coop, as it's virtually impossible to clean well enough to rid a place of all mites...just one pregnant one left behind can hop on a bird and re-populate the flock again in short order. Just treat the places where chickens are still and close to one another or use the same places, like roosts or nests. You can place sweet lime on the bedding and it can serve well in deterring mites and also will absorb moisture and keep down any odors.