There's an interesting concept, though I think this role is better filled by Shipyard factions on a server than as a game mechanic (I'm one of those people who would prefer player-driven/made features over possibly complex and rigid coded ones).
There is currently a mod that allows banking scripts if I remember. Name escapes me but it's used on Nasszone.
Neon's comment made me think of another suggestion about a "repair" function at shipyards (a possible error with it, but relevant).
But yeah, if a ship is over the credit cap, than server owners may not want people just spawning them in freely (exceptions of course), since they may stress the server. Ships so large they are over the credit cap could be built on-server, or bought with hollowed out parts (chunks of 20x20x20 taken out) and will be finished on server. There's also an economy reworking being planned I think, which would adjust the prices of blocks and ship BPs.
I dunno, just me rambling.