Pshaw. You need a colonial-minded guy in charge way earlier - Spain, the UK and the US would have too much influence in the region for Germany to end up with Hispaniola in the 19th century. Besides, Bismarck was not colonial-minded at all!
Maybe more colonial-minded Prussian monarchs force the Spanish and French to sell their halves of the island to Prussia in the 18th century? Maybe UK occupies Hispaniola in 18th century, and Prussia gains it in the peace negotiations? It's a start towards the German language aspect, at least.