Expanding on that idea, the undercut of the Excelsior
would nicely accommodate a cargo pod like the ones drawn up by Franz Joseph.
Indeed, if you scale the two DS9 Excelsior
kitbashes by their Miranda
style nacelles, you get a more modern version of the Franz Joseph cargo tug, with a somewhat more extensive grapple that happens to have the navigational deflector integrated to its bow... If you scale it according to the saucer, you can postulate a larger cargo pod for the 24th century, and then claim that the Excelsior
herself was also configured to tow such things, by virtue of that fancy grapplework inside the ventral cavity.