deep chin radiator like on a P-40 or Typhoon increases the side area in front of the CG of the aircraft
Yes, no, maybe????
The P-40 gets a bit of a bad rap.
When they changed the reduction gear on the engine the propeller moved up about 6 inches but the radiators/oil cooler stayed in the same place. The air scoop looks bigger on the P-40D/E and later but the curve at the bottom is pretty much the same size and the actual side area of the nose is just about the same. Since this was a P-36 with a V-12 instead of a radial the nose got longer by about 3 feet. Of course to was pointier
On the P-40 the radiators actually didn't hang below the bottom of the fuselage. Remember that the main fuel tanks were in the wing under the cockpit.
Typhoon is a bit different.
The radiator/oil cooler is hanging below the engine and does increase the side area.
however when they changed to wing leading edge radiators on the Tempest I
They didn't bother to change the fin and rudder.
You do need a certain amount of fin and rudder at low speed just handle the torque.
You also need a certain amount of vertical fin and rudder to keep the plane pointed straight at high speed.
The later P-40s got a 20in longer fuselage to move the tail fin back (elevators stayed at original location/distance from the wing).
The Merlin powered P-40s had larger scoop (bigger radiators? or air intake moved from the top to the bottom with little change in actual side area ?) but the later P-40s and Merln Powered ones also had several hundred horsepower more.
Propeller wind stream is doing a spiral down the fuselage and over the wing roots. Since the vertical fin is dealing with different amounts of pressure depending on the side of the fin and the speed you don't want to cut things too close.
Spitfires grew larger fins and rudders as power increased and their radiators as they grew larger, were always behind the CG. P-51 H got a taller fin.