Hey r666, is harvesting a must in a week? What would happen if you let them go a week longer? I generally let my plants go a little longer than suggested...
The point I am trying to make here is there is no need to harvest early. You can let your crop ripen to it's full potential if you are willing to be dilligent in treatment.
I have never used sm90. But BBP is one of my pot growing heros, so if he says it works, it works.
I do use Dutch Masters Zone and Penetrator, and I gotta say, it works pretty damn good, but it ain't cheap. There are many, many folk that absolutely swear by the milk treatment.
The point is that if you can give yourself a little over two weeks you can eliminate established leaf infections and sort of "dormantize" the pm for a clear and pm free harvest. If you do this then you gotta work quickly and get a jump on the treatment. What ever the treatment you go with, be consistant and don't stop the treatment until a few days before harvest, even if it 'looks' like you are pm free. Because you're not.
Increasing air flow/exchange is also a big deal. Do you have an exhaust fan? Do you only run it during lights out? Then run that sucker 24(-15 minutes)/7. Try repositioning your fan for better air flow. Try getting some heat into the growroom during lights off. These are all things that can really help, and really make a difference.
Also I think believing that bubble bags will separate pm from hash is a mistake. I am pretty sure those spores can go anywhere a trich head can go
Good luck!