Darrell Wampler, a big-city radio guy, got KTHO at South Lake Tahoe back on track with some distinctly small-town ideas.And now the broadcaster once known to Southern California audiences as "The Insane Darrell Wayne" plans to extend the station's reach into Reno."We don't want to be a Reno station," says Wampler. "We want to be an outlet where Reno people can learn what's happening at Lake Tahoe."In the past 20 months, Wampler has worked hard to make KTHO it's at 590 on the AM dial and 96.1 on the FM side an outlet where Lake Tahoe people can learn what's …