I have never had a problem with the trucool and hot weather. Last year I towed 8000# in stop and go traffic, 95* weather, for an hour in some construction traffic up in ftworth with my 2600 converter and my trans temps never got over 180 or so. Even when I was being retarded and seeing what the converter would flash to with that load it never got even close to what my trans did with the stock cooler unloaded. The trucool is no joke, even if the 6L80E runs a bit hotter you would still be fine.

The only time I'd worry about a truck with a trucool on it is if you've got a 3000+ converter, towing heavy, in traffic with really hot weather.

 

tag, for bigger cooler options

 

so is it just a matter of time till you need a bigger cooler?
I'm running a circle d 3000 stall, and I have the "HD cooling package", the hottest i've seen it get was beating the crap out of it on the dyno (tiny fan in front of the radiator) and that was 190* and it was a 85* day as well.
the hottest it gets here is about 90* so maybe thats why Ive been lucky?
I'll be going to visit / tour nevada and cali next summer so I'd hate to have to pull over and shut it down due to temp

 

I put in a BM 29000 btu cooler along with the stock aux cooler and in the summer it runs about 160 if I really push it it goes up to 190 doing some passes it gets to around 200 but as soon as I let off it comes back down. I liked tha pml cover and I also liked this one from BM
Cast Aluminum Deep Transmission Pan | B&M Racing and Performance Products