This one should look like a recombination of some of the ingredients from the last few Notebook Cocktails, mostly because it's exactly that.
2 oz white rum (Plantation 3 Star again)
1 1/4 oz cryo-cucumber juice (for which see N.C. #4)
3/4 oz mango shrub (nearly identical to the cranberry version from N.C. #1)
1 large dash Bittercube Bolivar bitters*
Stir well over ice and top with about 1 oz soda water.
*Troublesome brand specifications again, I know. The problem in this case is that I really don't know anything that is quite like these particular bitters. You could maybe try a dash each of Peychaud's and orange, but it won't be nearly the same thing.