MiMed,
I think it was 1diesel that mentioned doing the whole perfect environment for the spider mites to hatch, that reinforced what a contractor I know that does work for big grows in Cal, like JB do. They flat seal the whole rooms and paint and caulk every joint between the floor and the walls. They even caulk the outlet covers to the walls and they use Kiltz paint, like 3 or 4 coats. He even mentioned what you basically had happen. JB uses netting strung between pipes to support the colas. He specifically mentioned the like shits getting into those pipes.
Also these guys focus on keeping bugs out of the buildings, not so much the grow rooms because they have to pass Cali testing. I can only imagine they have orkin or someone spraying around the buildings every few days, so that basically if the bugs come near the place they are not going to want to come in. I have kind of started adopting this approach as well. I just spray outside all the time and use
pure crop 1 a couple times in case anything gets inside.