They could have someone in charge of decorating. (Paper or plastic table clothes with duct tape or bungees, and cornucopia centerpieces. Maybe gourds or corn along the center. A hay bale or 2 for the heck of it) they could do it during the regular lunch time. Maybe extend the lunch by 5 minutes either side.
At least you would only miss a few minutes right at the end of class vs. a constant interruption and useless day.
Find one of the artsy type teachers that you could drop a big in their ear. They may take the ball and run with it.
Make sure you have it known you want a good experience for the students and parents and arenít trying to kill it to save a day of work, but rather extend it to a larger ordeal with different types of interruption/staff involvement.