the fans are larger than the radiator.

they cost similar money to aftermarket "proper" fans aswell
so IMHO i'd just fit a single decent aftermarket one...

also its the FAN SWITCH which makes the fans go on/off not the thermostat, a thermostat controls the flow of water to the radiator and all its there to do is make the car warm up quicker when started from cold (well, that and regulate a constant water temp for the engine... lol)