Ernest Hemingway was a hardened drinker who also suffered from haemochromatosis (a rare hereditary disease that can lead to diabetes) so avoided sugar...
I really wanted this one to work as I'm a fan of coconut water cocktails, but unfortunately, I really can't say I liked it. It's missing sweetness and complexity that even the Angostura bitters couldn't compensate for. I added ~5ml of 2:1 simple syrup and it made OK'ish..