Wow, this is an interesting thread. There is very helpful info here. I don't have mites now, but have worked at prevention since the beginning when I got my new chicks and set up the coop that had been empty for several years. Prevention isn't a guarantee, but it helps.
Back when the kids raised many varieties of chickens, we got an infestation when they got an older silkie. Silkies are a breed that are very susceptible to leg mites. One of the reasons I now have Hamburgs for my main egg laying flock is their blue legs. Hamburgs scales are much tighter, and they do not get leg mites. At least, I have never seen one with leg mites, even when the rest of the flock had them severely. When we used to have lots of different breeds, we would have to go through all of them and coat their legs with Vaseline. That wasn't fun, especially in the winter. To make it easier to catch them, we'd go down with a flashlight and pick them off the roosts at night. Any feathers on the legs makes the bird much more susceptible and harder to treat. Yes, you can cut the feathers off. They will grow back at the next molt. Sometimes birds can get such a bad infestation that they can lose toes from it. So, better to loose the feathers than the toes. Just clip them leaving a stub so you don't make them bleed, don't try to get really close to the leg. Also, legs can be permanently scarred from the mites.
So, the short of it - we'd use the Vaseline, then when we cleaned out the coop in the spring and in the fall, we would paint the roosts with something that killed the mites.
