You can still move around the conning tower by using shift f2 in the command room then moving through one of the doors. The camera will show black but you should be able to see the conning tower above you. Just move the camera into it.
It's similar to in MS flight sim for those familiar. When inside the sub, both the command room and conning tower rooms are drawn in the one instance. You just need to go out of the visual limits to move between them.
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