Might seem strange but for more 6th generation submarine look maybe consider VLS only. There has been talk outside of the Navy of using the VLS silos on the Ohio SSGNs for launching torpedoes.
An internal hanger below the waterline would be useful for SOF craft like on the Yankee Stretch. You can also stick one or two man SDVs in external lockers or push then out the torpedo tubes.
Also consider thinking smaller. In this age of defense cutbacks a smaller, cheaper SSN would be the route perhaps taken soon.
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