heh..heh...heh....some simians are faster than others.
I have used a radiant electric heater pointed up from under the engine compartment, but I like your idea.
It should increase the temp inside the engine compartment by 20 to 30 degrees, maybe more if no wind.
There is usually no wind when it gets down to -40.
I would also recommend starting the vehicle first thing in the morning, if it was not left running overnight.