Does anyone know what the current size of our radiators are?? I ask because I am curious what CFM of air is crossing the radiator at 70mph or even at 45mph for that matter. I would be willing to bet that it is a lot more than the capability of the stock fan. I could be wrong but isnt the fan only really useful for like in stop and go situations, which then only really require a small amount of additional air flow for cooling because the heat generation rates due to engine load is a lot less?? Other than that I would think by simply driving down the road would create sufficient air flow to cool the motor. I have at least experienced this to be the case in my brother's jeep when his fan died on him.
I guess what I am getting at is, that IMO the engine does not produce a whole lot of heat that cant be removed by the 6000CFM that these fans produce even while towing at low speeds and then once at speed, the cross flow of air (I would think) would be more than the capacity of the fan anyways such as to basically render it in effective. Again this is my thought on the subject. I am happy to discuss and thanks to the OP for the start of the discussion.