Set up on a parade route in your town. Offer $1 off if this book is bought during the parade. Give away balloons to the children.
Sponsor an entry in a parade. All queen candidates are looking for sponsors and usually display your business name on the sides of their car.
Talk to parade organizers to see if you can offer a chance to be Junior Grand Marshall with each book sold. Then draw a winning name just before parade day. (You might work with a fund raising group.)
Make parade books with one of the friends being the Grand Marshall of your town's parade or of one of the big national parades. This is particularly useful if the adult ordering the book doesn't know the child's names.
Don't forget the smaller parades for holidays such as Fourth of July, St. Patrick's Day or Veteran's Day.