Hey boss, haven't seen you around for a minute, hope all is well despite the problems at hand.
Where are the plants in the garage at? Sounds like veg if you're considering the sulfur and bug bombs.
Are you running air exchange or are you sealed up and running and a/c? Reason I ask is since I started using a mini split in one of my rooms I noticed gnarly rh spikes after the lights turn out and the a/c is running less therefore dehumidifying less. Perfect circumstances for pm. Started running a dehuey on a timer to kick in when the lights turn off with a drain hose so I don't forget to empty the sumbitch. Bonus from this is the heat from the dehuey causes the a/c to cycle on, drying out the room even more, and helping to maintain my 50% lights off goal.
That being said, when I was getting pm a lot I figured out that it only grows within a ph range close to neutral, so I ph'd a gallon of water in a spray bottle up to 9-10 and hit the effected areas, it kept things at bay enough to get to harvest, though I can't speak on its efficacy when treating a well-established issue. Also, I found that, like anything else, some strains got it way worse than others.
As for the mites, I'm sure you have a routine down to get rid of them, if not I can share mine. I know i stopped seeing them once i got my lights on humidity in check (60-70% until the last few weeks of flower). Mites breed like crazy when it is hot and dry.
I've no experience with burning sulfur, though I beleive it's a no-no during flower. Also, it'll fuck up the sensors on environmental and co2 controllers if they're not removed before the burn.
Bleach is a staple in my Arsenal, never on the plants, but I clean everything with a 10% solution and fog all surfaces, nooks, and crannys with it using a paint sprayer.
Apologies for not directly speaking to your plan, but ime I found that if the same pathogens keep cropping up despite my continual curative efforts, then the root of them is usually environmental/cultural.
