I've seen photos of aircraft deployed smoke, apparently they
used both chemical tanks and even smoke bombs.  Bostons were
used to lay screens at Dieppe for the landings in 42.
     I think this would be kind of neat as it's just an ordnance thing
as opposed to a new aircraft.  Not sure how practical it would be
in the MA, but having a bunch of aircraft lay smoke over your
battlegroup sounds like a blast:aok