Water pump pulley ratio high RPM offroad

I run a 47re. Also fuel injected. 4.56 gearing. There is a small trans cooler infront of the rad. I need to move that so I get 100% cool air flow across the rad.

Now I do run the sand dunes in 4 low. Not sure if that matters...but again, I think I might be spinning the pump to fast.
Have you tried running in 4 high range? That would drop the pump rpm?
If it gets hot in high range its not your water pump rpm.