Place all ingredients in a blender and blend just until the melon is liquified (over-blending will make for foamy drinks!). In our Blendtec, this was achieved in about 10 seconds on power level 6.
Pour half the mixture into a cocktail shaker partially filled with ice. Shake until cold and pour over ice into salt rimmed glasses (run a lime wedge around the lip of the glass and dunk into Margarita salt) or serve with no salt.
Garnish with a lime wedge if desired. Repeat for the remaining two servings.