If HS band is first period, how feasible would it be for you to start rehearsals at 7 am? I did this at a small 3A several years ago. We started at 7, and continued through 1st period. Didn't have any rehearsals after school (students could come in for all-region after school). Every other activity held practice after school. This way you get roughly 10 hours worth of rehearsal, but only use up 5 of the 8 hours allotted for the week.