even then, I wonder where your anchor winch and chain go
to the front, the chain room have to be high than one deck, but it deck areal would be smaller.
The gun magazine size would suffer a bit, but not so much. there still plenty of room.
BTW. I have seen ships with guns that far forward, and that with 5" guns... British ship anyone!
But if I compare it to the Norwegian frigate, then the gun is only mounted in front of FN class gun position, compared to water line, But then FN is build to handle over 300 tons of ice on deck, and still be fully operational.