2002 Silverado Trans temp

[LT1 Burb]

I just pulled my 24' car trailer to LA and back with my C10 in it and need another trans cooler. My trans temp got up to 240 on my gauge climbing the Grapevine and Siskoyou's. It was 98 when I was climbing Grapevine, my trans never slipped and my fluid is fine. I have a 6.0 2500 HD 2WD with 4:10's in it. I looked at the location of the stock AUX cooler my truck has and the grill bar blocks airflow to it. I am going to install a TRU-Cool 40 and a Derale trans pan, has anyone else done this and had any issues. I did average about 9MPG over the trip which is pretty good as I was hauling 9500#.