The string-of-pods approach from the FJ tug might work for cargo but it strikes me as too fragile a setup for combat conditions and maneuvers. And the last design would still be easily capable of being built with other things in place of carrier pods below it, kind of like the Nebula variants. And I'd think a hardmounted connection there would also be better for a combat ship than a removable link... changing the configuration would be possible but would require a bit of drydock time.