Coarsely chop half of the melon; seal in a self-sealing plastic bag. Slice remaining melon; seal in a self-sealing plastic bag. Combine lettuce and spinach in a large bowl or container; cover. Combine ham and green onion in a self-sealing plastic bag; seal. Chill all ingredients about 1 hour.
Meanwhile, in a screw-top jar, combine pineapple juice, white wine vinegar, salad oil, and mint. Cover and shake well.
Transport melon, greens, ham, green onion, and dressing in an insulated cooler with ice packs. To serve, arrange melon slices on four plates. Add chopped melon and ham, and green onion to greens; toss lightly. Pour dressing over salad; toss lightly to coat. Divide salad among plates; sprinkle with almonds. Makes 4 servings.