It's true what racerx says about the CO2- it CAN be done, but you really need to know what you are doing.

Add a bit more breeze and keep your daytime temperatures low, down about 70 degrees. Mites LOVE very hot still dry conditions.

Ladybugs are wonderful.

Pyrethrin bombs combined with lower temps will really do a good job. Set off one bomb and keep temps low to make the mites reproduce MUCH slower. Then a few days later set off a second bomb. You should be much much better, and good to finish up the harvest. Hang no-pest strips to prevent re-infestation, and continue to use them in the future.