Simpson, married to his childhood sweetheart for almost 19 years, had walked out on his wife and kids and into the arms of a younger woman. The breakup surprised his wife, his friends and even Simpson himself. Looking back, he says, it was a classic midlife crisis.
In that we have already provided the definitive answer to this question elsewhere (relying on rum extract), we assume your follow-up is seeking a non-alcoholic substitute for rum (as extracts can be as alcoholic as or more alcoholic than the spirits they replace).
Here are my recommendations. Your basic ingredients are 80 proof rum, sugar and vanilla beans. At the recommended proportions, the rum and sugar are plenty effective preservatives. You can use either light or dark rum, but it should be a good call 80 proof rum and not a bargain bottom shelf rum. I most often use Ron Rico.