If you haven't shopped for a full-size truck in a few years, it's possible you've missed that there's a war going on. With each redesign, these light-duty pickups—like the Ford F-150, the Chevy Silverado 1500, the GMC Sierra 1500, and even the 2013 Ram 1500 SLT that we're driving now for 30 days of up-close coverage—have towing and...