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).
I would substitute a caramel glaze for the bourbon glaze and use a non-alcoholic-based vanilla extract for the cake itself. Since you are making this for a person who cannot have alcohol, be careful using extracts as flavorings are often extracted with alcohol (ethyl alcohol or ethanol, it's the same thing). Caramel!