Sorry to hear the tales of woe with PM. I've been there a couple times.
I found mixing sulfur with water (a few drops of soap for surfactant) to be very helpful for plants in veg. Wear a mask when spraying and don't lick your fingers!
It can burn them though, so best to test your mix ratio on a plant you have spare clones of etc. Also, seedlings and young clones are more susceptible to being burned. I would never spray sulfur on plants in flower past the first week or two, strain and flower formation being the determinant of when to cease.
A dehumidifier set at 50% humidity and fan running during lights off in the flower area have helped me get rid of the PM problem. (fingers still crossed...been about a year).
Nobody wants to shut down and REALLY start over, but that's what I did, super cleaned veg and flower area, new plants, cleaned lights, new fan etc.
Side benefit of the sulfur is it ain't too tasty to spider mites either. If you're worried about residual sulfur on leaves intended for extractions or butter after harvest, a water rinse right before they go from veg to flower does the trick.
Sulfur comes in premixed concentrate or powder form, and it's inexpensive.