FROM THE COAST

Getting ready to plan your summer vacation? Hobo Times, a Los Angeles-based newsletter with a steadily growing subscription base of 3,000-plus, suggests a real adventure: hoboing, riding the rails, sleeping under the open skies. The newsletter is popular among-you guessed it-yuppies. (And you thought they were dead.) For more details on the hobo life, write the Nat onal Hobo Association, World Way Center, Box 90430, Los Angeles, CA 90009.