"Proceed as the way opens" is how William Least Heat-Moon put it in his book, River Horse. The line becomes a sort of mantra for Pulitzer Prize-winner Elizabeth McGowan, a melanoma survivor. Having been given a five-year clean bill of health, McGowan decides to bicycle all 4,000 or so miles from America's west to east coast. For her, there are multiple reasons for the exhausting trip. She wants to help other melanoma victims, and sets out to use...