I know that corn meal and corn flour are a bit of a canard when it comes to Chicago style deep dish pizza. Putting that aside, you should seriously consider trying something. The other night I was making a deep dish with 20% semolina according to the BTB recipe. I was having dinner guests over. I went to weigh out the semolina and found that I only had half of what I needed. I didn't have time to run to the store for more, so I substituted corn meal for the other 10%. I took the corn meal and ground it in the coffee grinder to make it a little finer. I also added a few drops of yellow food coloring to the dough, as is my custom.
The results were really, really, REALLY good. The dinner guests raved about it. My wife loved it and she eats my pizza all the time.