just some suggestions, but maybe the rule should say, that you can only non combat move through a narrow strait if both adjacent territories are not hostile. They can be friendly, neutral or yours, but they can not be hostile.
Now, if one or both adjacent territories are hostile, you must combat move through that narrow strait.
I dont know exactly how this should be played out, but I believe the owner of the hostile territory should be able to scramble fighters, and the attacker can of course use his fighters as escort, just like in the real war Channel Dash. Maybe even a minefield rule, but 2 or less as hits are too much, maybe each 1 is a hit, same as AA fire. We could even use some modified rules from A&A Guadalcanal and let Artillery units on land act as coastal guns and fire at the ships. The only drawback would be like you want to cross the English Channel, but Germany has stacked like 20 Artillery units in Normandy, or something.
