[Xrati]

You could shorten the nose section and narrow mid section leaving the engines as need for ship class. So it would look like the 2nd pic, but with a smaller nose, thin mid section and whatever amount of engines you think would accommodate the class. Just like the Federation ships are all from a base concept of saucer section, main body (mid ship) section and warp nacelles.

In an actual concept of that fleet, I would think that the escorts would carry fighters that would act as the CAP while a strike force of Vipers was on an attack run. So all the ships in the fleet might have some capacity to launch or recover vipers for refuel or repair purposes.