In reality it doesn't matter how much heat you're generating, it's the diferential between how much heat you're generating and how much you're dissapating. If nothing is getting through the dashboard, then any heat generated just builds up, increasing the temperature. In most cars, the area under the steering wheel in the footwell is open, so any heat generated by a motor would have somewhere to disipate to.

As other have pointed out, adding any sort of fan or heatsink isn't going to do any good if the surrounding air is just as warm. If your fan gives you any benefit from evaporative cooling you've got bigger problems. Your only option is to find a way to get air from the passenger compartment to the empeg. Any room for tubes to the footwell?

Matthew