Sure, I do not see any problem to make an arrangement. The Netherlands need the trade via Rotterdam and Amsterdam and it is also beneficial for Germany. This would work regardless if the Dutch are in or out of the Union. But I cannot see how Germany could not function w/o these harbors???

Regarding the USA: I always wondered if I heard Brits (English or Scottish) talking about Americans. They all seem to think those are barbarians with nuke. Guess the Brits hate them more then the Europeans.
I think the British politic is already very American. Economic ideals are similar and the it seems as if the British foreign ministers do not make any step before asking their big brother. Looking at the spy programs it seems as if they also have the same view on human rights.
However I do not think that the US would led England in. Why change things? GB has a similar status as Puerto Rico. It follows the orders of the US government, has no right to vote for Congress or President but has the priviledge to keep the Queen.