In a large bowl, stir together 1 cup of the bread flour, the whole-wheat flour, gluten flour and yeast. Add the warm water, sugar, oil and salt. Beat with an electric mixer on low to medium speed for 30 seconds, scraping side of bowl constantly. Beat on high speed for 3 minutes. Using a wooden spoon, stir in cornmeal, oat mixture and as much of the remaining bread flour as you can.