Martha concocts three low-calorie cocktails: a burnt-orange highball, a raspberry-lime gin and tonic, and a watermelon-ginger "mocktail."
Place Truvia, watermelon, ginger, and lime juice in the jar of a blender; blend until smooth.
Fill a cocktail shaker with ice; transfer watermelon mixture to cocktail shaker. Cover and shake until well combined. Strain into a chilled champagne glass.