I don't think new ships are really necessary. The Maelstrom and Pandemonium could have Large Universal Mounts instead of their Large Hybrid Mounts.
I have tested by making the mounts on both the Maelstrom and Pandemonium Universal and tried them with both vanilla and mod Large Missiles. And they work pretty great (DME Chasseurs on a Pandemonium is pretty sweet), specially with how good you can set up the other mounts (Hybrid Mounts really allow a lot of versatility. Universal just takes it to next level!). So i don't really think new ships are really needed.
At most the Daze and the Haze could probably get 1 mount reworked in size, as i feel they are the only 2 Cruisers that could actually put a Large Mount to use (And Universal Mount, maintains the versatility Diable is known for). It just gives the option for Large Missiles if you feel your fleet needs it. There are vanilla Cruisers with Large Mounts after all (Apogee's and Gryphon's Large Mount is a Missile Mount) so i don't think its impossible for Daze and Haze to get a Large Mount.
Of course the easier option is to limit the Large Missiles to the Maelstrom and Pandemonium. And just change the type of mount on the Cruisers from Hybrid to Universal (not all mounts of course for balance purposes) so that you could throw some Medium Missiles and have a Missile Cruiser (for the memes i changed all the mounts to Universal, and its pretty fun to run around with Missile Spam on Daze and Haze XD)
I think the hardest work overall would be with the actual Large Missile Weapons themselves. But since they are just Large Versions of Thunderbolt, Banish, Plover and Thrush, it shouldn't be that hard to balance. (Specially for you, since you're probably one of the best modders around when it comes around balance and tweaking.)
And of course adding Missile variants on the variants file, so that the AI actually runs them.
I would love new ships as much as anyone. But i don't think its necessary, the versatility of Diable itself makes it viable with the current ship lineup.