In 2012 on a very hot summers day we had to change our route from Barcelona to Arles.
Circumstances dictated a heavy right foot, shortly after crossing into France we came into heavy traffic, speeds were down to 20ish then 2 hours plus of stop / start in stifling heat.
On the same trip got stuck behind a slow procession in the Algarve for over an hour, in extremely hot weather.
In the Pyrenees we got stuck on very steep climbs behind slow trucks etc in high temperatures.
At no time did my DVA K series on throttle bodies, high lift cams, power speed 4-2-1 exhaust etc over heat. The fan did come on a number of times, but you'd expect that.
In my experience the only ducting needed is a radiator bypass to take cold air to the air filter on a front intake air box.