If it were possible to substitute that would be the sure way to go. There isn't time to get quickfix in hand before the test unless they have it a local headshop, so you'll have to ask someone that YOU CAN RELY ON BEING CLEAN for some piss. You could possibly do the dillution thing, but the thing is you need to know what a home test is showing. Get to a local chain drugstore and get a home test about $15-$16 dollars and try it after drinking a liter or so of water, if that shows a line then there is hope for dillution. Just follow the dillution sticky on the morning of the test. If not subbing is your only hope. Is it possible to stall the test a few days?? That could make it happen for you. The reason I am skeptical of the dillution is that a bro of mine smoked a few pulls on a blunt on fri and dropped dirty mon, with a similar build and similar abstenence circumstances to yours.Good luck and post back, it may help someone else.
STIMPY21