I'ma call rank on this one. Rum, orgeat syrup, a really good triple sec (you'll have to use cointreau otherwise), smidge of lime juice, two dashes of bitters. Maybe a sprig of mint for garnish. It's hard to get all that stuff together, but I promise you'll never miss the fruit juice -- and it's historically accurate to boot.

... though it's hard to argue with 50 rums simultaneously. Carry on, then.