Well I googled Lane Cake and apparently the filling also takes brandy and some people have used the real thing, whether it be Brandy, bourbon or whiskey. One lady said they put a full glass of wine in the filling, but most suggested no liquor in the filling if being served to children. From what I read, I don't see why you can't use Rum flavoring, you can tell everyone that you decided to put your own spin on the recipe. After reading the recipe, I just might have to make one someday.