Personally I don't even 'go thru' the radiator. I'd bypass it completely, and just loop the tranny lines to the cooler and back.
My personal preference. All the radiator does is heat it up. Coolers are for cooling, right?
Granted, I've only been a tech for 30+ years, but I"ve never, as in NEVER had an overheated concern with any of my transmissions, in ANY vehicle.
Don't wanna get into a peepee match with anyone, again, just stating my .002