To get in the fall theme of things, how about pumpkin rolling relays. Get some nice sized pumpkins, divide participants up into teams, set up a course and have players roll the pumpkin through the course, then hand off to the next teammate for the return trip. Keep going until one team has gotten all of their members through the course. Pumpkins don't roll straight, so this could be pretty funny!
In place of apple bobbing(too germy) try floating the apples in a tub of water and have participants try to stab one with a fork.
Make cornhusk dolls, fall garlands with dried flowers and mini corns, pumpkin/squash/gourd painting.
Have a chili-cookoff or a recipe contest/tasting of things made with pumpkin or apples.
I always think of bonfires with hotdog roasts and marshmallow toasting(s'mores-YUM!), but even with adult help requirements that could be too hazardous. I have done s'mores on a gas grill-wrapped them in foil and put them on the grill to get all melted. That could be a thought for a snack to sell. You could even do the hotdogs on a grill. We have some businesses in our community with the big grill wagons-maybe look for one in your town and see if they would loan it to you or better yet, run it for you.
We have a fall festival every year, but are tired of the same old games. I would like some ideas of things to do, we are a small PK-6 school with only about 6-8 volunteers. Thanks in advance!!