Thanks for including my alternative recipe in the description. However, I think I either communicated it badly, or there was an error in its transcription. I think it should read:

40ml (1 1/3oz) Navy Rum
10ml (1/3oz) Lime juice
10ml (1/3oz) Sugar syrup (2:1)
30ml (1oz) Water
1 dash Aromatic bitters

As in, I promise simply making a smaller drink (in a regular rocks glass); and crucially one with a total of 18.5 grams of alcohol (down from close to 28!)