The Aquarius could work for that. It's basically a Defiant with the crew quarters, sickbay, and anything else that can be handled by the Odyssey gutted out. Could work as a frigate pet like the Vo'quv's BoPs. But on the other hand, it's also extremely specialized to fit in that slot on the Odyssey instead of an open flight deck like the Atrox's.
It's a shame you can't use the quad cannons from a T4 Defiant on a Fighter.
Actually, I don't know when it happened, but it seems Cryptic maybe stealth changed the Quad Cannons to fit on fighters. I just happened to be reading the tooltip and noticed it mentioned "fighter". So I put it on my Peregrine and it fits fine. I swore it couldn't be mounted before so I was quite surprised when I saw it.