Wow! We have a debate going! Differences of opinion! Wondermuss! Possibly productive, even!
Air flow is indeed important for a cooler to be useful. From what little I have learned, it can be helpful to think in terms of high-pressure and low-pressure areas. Air likes to flow from a high-pressure area to a low-pressure area. The middle of a flat surface facing forward, such as the radiator area of a car or bus, rams straight into the air so it is a high-pressure area -- perfect for inward flow thru a cooler.
The rest of the air must then yield to the bus, and this air is forced to the sides (and up and under). This air collides with the air that tries to flow straight along the side of the bus, and the sum is an angled air flow at the corner of the vehicle. So right around the corner, where the driver is hanging his elbow out the window, is a low-pressure area -- notice how light debris like gum wrappers blow out the driver's side window.
(Something else, is an aerodynamic phenomenon called the boundary layer, but now we are getting beyond the scope of this thread.)
The spot I have in mind for a tranny cooler is in the low-pressure area behind the front tire, and the air flow would be outward. This is an uncluttered spot between the tire and one of my gray water tanks, close to the tranny. I'd just cut a big hole and install a stout screen.
Way back in car mechanic school, they taught me to put an extra tranny cooler before
the built-in cooler in the bottom of the radiator. The reason was to keep the tranny from running too cool under light load in cold weather.
Yes, Millicent has a belt driven fan on the front of the engine. With a thermostatic clutch. And I dread the day that I set out to replace the belt or do anything else in there, because the radiator will have to come out for access. That's my main reason for not putting any more Stuff up there. If you wonder about the Peterbilt grille, it is held in place by spring loaded latches, like model A Ford and Jeep hood latches, so it comes off in seconds.
On that note... Most people are not aware that the Blue Bird school bus company also builds motor homes. The brand name is WanderLodge. These days, the motor homes are unrelated to the school buses, but they started out as a fancy variety of the flat nose school buses, including the front engine type. These WanderLodges, or at least some of them, have the radiator mounted on a hinge for engine access. It may be an aftermarket conversion. I have never looked at this arrangement up close, so I don't know how they hinge the hoses, but I sure wish I had this. (One more thing to invent and fabricate!