Extended trips sour as quickly as the dirty laundry bag on board. Most of the methods of dealing with the load - expensive washer-dryers, a bucket, going home - are about as enticing as giving the previous day's clothing another round. The Laundry Alternative Inc. cleans up the mess with Wonderwash. The Wonderwash weighs less than 6 pounds, is smaller than expensive washer-dryer units and doesn't need electricity. Better still, the washing process takes about two minutes and uses 90 percent less water and detergent. Prices start at $42.95.