As long as you have plenty of hides you should be fine. Good cheap hides to use are paper towel rolls. You place several around the cage so they can go from one side to the other.
I just bought my two corns back in Sept and on is in a 29 gal and the other a 20 gal long. I have 2 hides in the 20 gal and the substrate is about an inche think. I also have fake plants, the long vine looking ones with the leaves stuck to the side and provide cover on the bottom. He likes the hiding under the water dish though. Both are doing great.
Jean