Around halfway through that paper they write that a dosage of 4% peppermint oil is the most effective for spider mites. This is the first time anybody has given us a real idea of how much to use 
. I’m looking at companion planting as well. According to their research mites hate the smell as well so a few well placed peppermint plants among your grow could work really well. Found this as part of an article on peppermint, interesting 
The “pepper” part of its name is particularly apt since it has a spicy, pungent flavor derived from a unique combination of menthol, menthone, and menthyl acetate, as well as limonene and other terpenoids.