We also have no urban cooling kit on our early 2012 car and have only encountered skip-fire once when stuck in a long/slow traffic jam. Given that limited experience (inc running in a hot Southern France summer), we installed a simple fan mounted on the grill inside the cowl and switch this on when in jams as a preventive measure. Another factor that helps may be the G56 exhaust which presumably takes more heat away from the engine....
Likewise - I have my own manual fan mounted on the grill to blow a lot of air onto the back of the engine when required. But the biggest cause of heat build-up for sure are the exhaust restrictions, so once they are gone, most of the problems are alleviated too in my experience. Note that for the grill-mounted fan to be effective it needs to be able to draw air from behind the blades primarily, necessitating a hole to be cut in the solid front panel on the bonnet. Without this air routing, it would otherwise have to be drawn around the sides of the fan and this is very inefficient. Moreover, clearing hot air from the under-bonnet area can only help the overall cooling process, as I am constantly surprised just how hot that oil tank makes the under-bonnet space after a decent run.
