sorry to be a little late.
You do want your trans and other fluids to actually get hot, hot enough to boil off the water that condensates when it cools.
I always try to run the radiator (water heat exchange) first then to an air cooler.
The water cooler is way more efficient.
Then use the air cooler knock down the temperatures a little more.
The air cooler don't always get the best air flow especially from the fan which we need the most when rock crawling.
But the fan is positioned correctly to cool the radiator.
And the radiator will help get it to operating temp faster. Some transmission will operate in worm up mode until it gets to operating temp.
They actually sell thermostats for trans coolers.
If you have a multi-meter with a thermocoupler you can just tap or hose clamp it onto the tranny cooler line.
If you have A/C that doesn't work you can use the A/C condenser as cooler, free, placed perfect, and large.
As for a pan drain.
I always make my own. I drill a hole to let the fluid out then either just weld up the hole or weld on a nut and make a my own drain plug.
Just my 2 cents if is even worth that much.