@janiewalker - sounds like you’re on top of the printing - what a hassle though!
@homerdog FWIW, Instructions from Scholastic that we got (paraphrased) stipulate that 2D winning entries must be matted with a 2" border and a hard backing such as mat board, cardboard, foam core (but not wood, Masonite or plexiglass. For delivery to exhibition venue, place between rigid boards. Use fixative for charcoals and pastels.
This may vary according to region, however.