On offense, we play 4 to 8 measure shorts. When the band gets a 1st, 2nd, 3rd, or 4th down, and some 2 measure quick chants when we want something super quick. All of our offense sets are a few seconds long and it's after the play is over. Each one has a chant, and the community knows and loves them. Our coaches have been okay with us playing short team spirit shorts on offense - they actually really like it, and so does our administration. If timed right, it will be quick, won't distract your football team when calls are being made, and will be over before the ball is snapped.
When your team is on defense, play to your heart's content.
Our community is really happy with this format, because it means that we play often and at appropriate times.
But yeah according to the NCAA rule, it's like you can never play. I have always just done whatever the athletic director wants us to do and just go along with it. If my athletic director ever said "don't play on offense anymore", it would be a thumbs up for me and just sit and relax. Because, I mean, ...battles, priorities, etc.
(...having a ref come over to tell you the other team is complaining that your band is too loud is a rite of passage...)