Here's the challenge and plausibility check- having the English Commonwealth established after the ousting of Charles I and the United Provinces of the Netherlands, retain generally positive, and always peaceful, relations with each other, on the basis of basic ideological compatibility (Calvinist religion & Republican or non-monarchical political principles among the elites) that somehow prevents clashes of commercial, naval and geopolitical interest from causing wars in the 1600s. How could the English Commonwealth/Protectorate and the UP go about managing their competing interests without resort to war?