At the school I taught at, there were 3-4 teachers on each grade level. One teacher from each grade level was expected to attend PTO meetings and fundraisers. In this way, we could take turns and only had to go to 1 out of every 4 events, but the teachers at the school were still represented. Also, when we attended something extra like that, our principal gave us a coupon to wear jeans one day, which was a fun little reward. Maybe the OP could suggest something like this to the principal.
Teachers do have families, too. I hated the days when it was my turn to go to PTO meeting because after being at school all day, I had just enough time to pick my kids up from daycare, drop them off with my DH, and then head BACK to school. They were often in bed by the time I got home. Something to keep in mind.
ETA: The above is the reason I decided to quit teaching and stay home with my kids.