The TOS Enterprise seems a bit small so I propose doubling the ship's size in height, length and width. That would give you four saucer rim decks instead of two and allow all this expanse that the movie would show and still be smaller than Enterprise D. It works out to an 800 foot diameter saucer rim a 680 foot plus secondary hull and an overall length of about 1900-2000 feet. In view of the huge size of the hangar deck, scaling up seems to make sense to me.