Break down the watermelon by slicing it into 8 equal, and more manageable, pieces. Carve out the red and pink flesh from each slice. Using a juicer, juice enough flesh to produce 3 cups of watermelon juice. Reserve the watermelon juice for the pickling liquid; the remaining flesh can be eaten or saved for other uses.
Carefully fillet the white rind off the green skin, discarding the skin. The rind should be only ⅛ inch thick and have no green color remaining. Cut the rind into ½x2-inch rectangles.
In a large bowl, add the watermelon rind pieces and toss in the salt. Let sit until they have softened slightly and seasoned, 2 hours.
Rinse the salted rind pieces with cold water, then drain and return to the bowl.
In a medium stock pot, add the reserved watermelon juice with the lime juice, maple syrup, rice wine vinegar, white wine vinegar, cinnamon stick and makrut lime leaf.
Bring the pickling liquid to a boil and pour over the rind pieces.
Allow to completely cool and store in the refrigerator until ready to eat, at least 48 hours.