Heheh. No, they don't. I can do this now, in fact. In Names.cfg you add new unit types. The ships appear, but they don't get a rec manual entry.
I have plans to use this

It's in an old thread on adding ships in the mods forum.
;Merchant ships
Type100=Replenishment
Type101=Tanker
Type102=Cargo
Type103=Troop Transport
Type104=Coastal Vessel
Type105=Life Raft
Type106=Survivor
Type107=Environmental
Add:
Type108=CargoEmpty
Type109=CargoLoaded
You'd have to clone the ships, make the changes, then explicitly add those types into the campaign, then.