I like Chuck's idea. Just route from one end to the middle, flip the board and route from the other end to the middle. Better yet, set up a stop that will keep you from going past the start mark. Then start a tiny way from the "good" end and then climb cut back to the end. Flip the board and repeat.
“We should be careful to get out of an experience only the wisdom that is in it and stop there lest we be like the cat that sits down on a hot stove lid. She will never sit down on a hot stove lid again and that is well but also she will never sit down on a cold one anymore.” - Mark Twain