Anyhow effectively cooling a buried radial is not any easier than cooling an air-cooled V-12,
and there is no reason that Lawrance type air-cooled cylinder design (the basis of all Wright and P&W
air-cooled radials) could not be successfully applied to the V-12 format. Wright built the air-cooled
V-1460 and V-1560 engines in the late-twenties and there is actually no technological reason that
development of high-powered air-cooled V engines couldn't have continued, if so desired.
Well, actually, cooling a long row of cylinders gets to be a bit more of a chore than cooling a radial, especially when you get to the cylinders farthest from where the cooling air enters (one reason Lycoming's IO720 isn't/wasn't as popular as it might have been, that fourth row of two cylinders needed extra cooling scoops since air coming in the front of the cowling really wasn't reaching them, even with good baffling directing the flow). The same applies to multiple rows in a V or IV configuration.
Operative term is
buried i.e. like the Piaggio P.119, and I'm quite familiar with the ins & outs of air-cooled
engines in their various permutations, in the real world. The Armstrong-Siddeley inline cylinder radials had
cooling problems, thus the big scoop arrangement on the Whitley testbed for the Deerhound. The air was
brought in behind the spinner and then ducted over the cylinder banks from the
rear, exiting at the
forward end of the cowling.
The Gypsy-12 powered D.H. 91 and D.H.92 used a similar reverse-flow ram-air cooling system.
So as we are talking about fantasy aircraft, why not a buried air-cooled V-12 naval fighter with reverse-flow
ram-air cooling? No one has said it would have to be a
successful design.