I see two, opposing, points on this.
On one hand, you'd use as much automation as possible to reduce the manpower requirements of the ship. For the same ship, adding automation, and thus reducing crew complement, would free up space for the remaining crew
On the other hand, you'd reduce the overall size of the vessel to match the volume demanded by the manpower requirements, plus materiel, that the ship has to accommodate.
So, presumably, a 30th century craft would be no more pleasant to operate than a 20th century craft. You'd only build it as big as it needed to be, at least so long as it was a working ship.
Of course, with terraport cages, if
they can't be blocked, there's no real reason to put the magazines, or even the quarters, aboard the ship. That would allow for tiny, gnat-sized, ships that could dish out damage on par with much larger craft, both in terms of instantaneous damage and damage over time.
Ships of such a size were also notoriously unpleasant vessels to sail, due to the cramped conditions and large quantities of machinery. And most of the Kitesfear is taken up by its annie plant...
"...a compact mass of machinery not meant to keep the sea nor to live in... as five sevenths of the ship are taken up by machinery and fuel, whilst the remaining two sevenths, fore and aft, are the crew's quarters; officers forward and the men placed aft. And even in those spaces are placed anchor engines, steering engines, steam pipes, etc. rendering them unbearably hot in tropical regions."
"Being in command of a destroyer for a long period, especially in wartime... is not very good for the health. Life on a destroyer in winter, with bad food, no comforts, would sap the powers of the strongest men in the long run. A destroyer is always more uncomfortable than the others, and rain, snow, and sea-water combine to make them damp; in fact, in bad weather there is not a dry spot where one can rest for a moment. Yesterday I looked at myself in a mirror for a long time; I was disagreeably surprised to see my face thin, full of wrinkles, and as old as though I were fifty. My clothes cover nothing but a skeleton, and my bones are full of rheumatism."
But then I don't really recall how big the company was back on those days. It might have only been a couple of dozen people? I wonder who'll be posted to his new command, maybe Ennesby will even get a hull under him again!
Edit: although my knowledge of warships only goes to the early 20th century, a quick google reveals a modern ship of twice that length (and of course the Kitesfear is much wider) can accommodate up to two hundred.
The Toughs have always been under a hundred people even when they had the 3 ships at the beginning of the 15th book. Back when they had the Kitesfear they where much smaller than that. While a Fletcher had a crew of over 300. So I don't think it's going to be cramped.