Had this 'signature cocktail' out one night and really liked it.  
You can tell it gets inspiration from a traditional dark and stormy.
 
The menu at the restaurant labeled the ingredients:  
Goslings Black Seal Rum, Apple Cider Molasses, Blenheim Ginger Ale, Lime
 
I have no idea what Apple Cider Molasses is.  My version tastes almost exactly same, 
I just figured the apple cider molasses added sweetness, and so I used some other sweet things...
 
My version, lets call it the "DS2":
gosslings black seal rum
sweet vermuth & /or ruby port & or southern comfort (something to add unobtrusive sweetness) 
lime juice (roses or fresh or both. generous amount, like a tablespoon or more) 
ginger tonic, or fresh gated ginger  (I get my tonic at the wine cabinet at north point, 
in Reston "Shrub & co, spicy ginger tonic".  it's an expensive bottle at 20 bucks, 
but lasts a long time and it's totally worth it, as compared to grating fresh)

shake vigorously with ice, pour in a glass, and top with ginger ale.