I have made dilly watermelon rind pickles but they were vinegar based, not fermented. The benefit was that after boiling the jars and storing them for months, they were as crispy as fresh cucumbers, whereas real cucumbers would have been more difficult to prevent from going mushy. I basically think of them as phony crunchy cukes. I put dill, black pepper, chillies, salt and half-half vinegar-water, and they were one of those yummy dilly pickles, you know. I'm sure you can ferment them like cucumbers, and they will stay crunchy more easily than than cucumber do.