Worthy variant of the Last Word, and the extra rum certainly works. When made with lemon juice instead of lime, this is called Le Dernier Mot.

Loved the idea of a Last Word made from agricole rhum. As with all Last Words, I found it a bit sweet with the two liqueurs. Did try upping the rhum to 1 oz which dropped the sweetness level a bit. Next time would increase the lime juice to get a more balanced cocktail the way we like it.
However, it is delightful as per the recipe.