2 inches of substrate is way too much when using a UTH. If you crank the heat up to get your 85 degrees on the top layer of substrate the actual bottom of the cage will be too hot and when the snake burrows it can burn itself.
That's what I'm worried about. The care sheets say to have a few inches of substrate because corn snakes love to borrow. So should I just set the UTH to 85 and hope that if the snake gets cold it'll burrow?