I think the problem on a car, is where do you move it to?

I think I've seen some of the southern guys say they have moved thiers with sucess. Perhaps one of them will chime in.

I mounted a remote trans cooler on my tow rig winni.

I used a trans cooler from a 06 f350 superduty diesel. It's about the same size as a K car radiator. That said, I mounted an electric fan on it from a K car. I moved it so it is behind the rear diff, under the motor home.

It's not rocket science. If the cooler is in front of the rad, it takes the heat out of the trans, and puts it straight back into the rad. By moving the cooler, so it is totally independant, it only removes heat from the trans. Does not ad it to the motor. Preheated air for the radiator can't be effecient, as seen when the AC is on.

How good does it work? Well, I only kick the fan on, when on the hills to help keep the trans from boiling(common in motor homes). Keeps my engine temps constant when pulling the car.
When I got to a 50 mile flat stretch after a bunch of hill climbing last year, I kicked it on just for fun. Dropped the engine temp 10 degrees.

I'm pretty sure there are small coolers with electric fans already built on them available from speed shops, online etc..