When Art Murray first heard that Cameron Crowe might headline one of his immersive Healdsburg events, he dismissed it as far-fetched. Murray’s T.O.W.N. experiences — equal parts dinner party, performance and elaborate staging — have over the past three years included a sushi boat river, a drone show, a sloth, an animatronic yeti, burlesque dancers and even a staged bank robbery. On April 17, however, that pipe dream becomes reality.