[Suggestion] Unique Naval Units in 1943

I noticed that in 1939 and 1943 conquest scenarios every nation can get its unique air and land units after upgrading airports and factories to level IV, once the technological level reach 8-9

But what about unique naval units for UK, Japan, USA and Italy? You can't upgrade ports at all so these units are unavailable in those years of conquest, even though they do appear in the WWII europe/pacific campaign's scenarios of the same years

It is unfair especially for Italy since you can produce the super submarine only in 1980 conquest

I think these units should be buildable at least in the 1943 conquest, it will make the gameplay of Uk, Japan, USA and Italy a bit less boring and different from 1939. I doubt it will cause any balance problems after all

What do you guys think?

ps: sorry for my bad english