Schools (some) are already determining their own guidelines. Trenton Peabody, Union City, and Milan have been practicing for weeks already, and because TSSAA deferred the authority to "local policy", they're completely justified in doing so. Other local schools however, cannot conduct any team sports related activities, and would face penalties if they did so. TSSAA has an obligation to it's member schools to coordinate sports related activities (Article1 - Section 3), and has blatantly refused to do so for fear of liability.
Consider the school closing date, consult Dept. of Health, Set the parameters (dead period/helmet/full pads/ect…), set the season, and THEN the schools have the choice whether or not to allow practice with some idea of what everyone else is able/not able to do. Member schools pay a fee to TSSAA for just such a service, not to disappear when nobody knows what to do.