What if Germany already controlled Denmark?

Could the Baltic plan work if Denmark had sided with Germany or been absorbed before the war?

German control of both shores would turn the Danish Straits into a fortified passage like the Dardanelles and remove the premise that makes this Baltic option possible.

German control of Denmark creates a different counterfactual. Germany would fortify both sides of the straits and directly control the passage. The Royal Navy would have to fight through mines and shore batteries in a narrow channel, recreating the central problem at Gallipoli. Neutral Danish territory is a necessary condition for the proposed surprise. Once that condition changes, the Baltic plan ceases to be a small variation on this scenario.