The at idle thing with the fans, is not because I am thinking that the truck needs to make power while it's sitting, was just wondering if the fans would help keep the metal cooler that way it will be more effective when you do start moving, seeing as it would heat up quite a bit from the engine and radiator being so close. Fans would be cheap and if it helped at all it would be worth it, I would think. Especially on a HOT day, at the bottom of a hill, with a heavy load, and trying to get moving from a dead stop. For those of you who live in the hills and know how they like to put stop lights at the bottom, this may make sense to you too.
Also instead of fuster clucking it against the radiator, what about mounting the IC right behind the front bumper, face down, with a J shaped scoop to catch the air and direct it up through the IC, thus keeping it cooler and away from the radiator. Could put chicken wire and screen over the opening to the scoop to protect it from road debris. Just a thought. Could fiberglass up a scoop pretty easily.