You want a place where people are suposed to live, correct? In order to make room for that several key components of a military ship would have to go, such as the power generators which are connected to the turrets, armor plating, and structual hardpoints.
To make a long story short: It just won't go. If you're really keen on this idea, however, and simply MUST have a military ship then you could use two less turrets and never use an armor upgrade in order to reflect those modifications. (And i don't care how skilled the team of mechanics and engineers who did the upgrades were, it's just not possible to retain ALL combat capabilities of a ship while having "luxurious accomodations" inside of it.)
