My truck is a 2013 Express CC with the 5.7, 2WD with 3.55 gears and the 6-speed. I just completed a 3100 mile round trip from Wichita, KS to the LA California area and back. I delivered a super cool 1966 Toyota FJ to Scottsdale, AZ on the way there, and I brought back a bed full of furniture and a Toyota Corolla on the way back. The Corolla literally had about 800 lbs of mother-in-law stuff inside of it so I was towing between 5000-5500 lbs the whole way.
I had massive head and crosswinds most of the time, but I ended up averaging 9.8 mpg for the entire trip. That was driving 75-80. I-40 has some really long 7% grades in NM and AZ. The absolute highest transmission temp I saw was 155 when the outside temp was about 80. It averaged 130. I messed around with the tow/haul button on flat portions and found it really did make the tranny run a little cooler. Other than that I ran tow/haul the entire time.
Right before the trip I put the Airlift 1000 bags on. I also installed the air compressor. I can't remember the exact one a the moment but it is the heavy duty one that runs two different lines. I hooked up each bag independently. It was super cool being able to fine tune the ride while going down the freeway. I would strongly recommend these bags to anyone who ever tows with a Ram 1500. It makes the truck behave so much better.
I routinely tow for my side business (I build fences) so I'm very well aware of my truck's abilities and limitations. Mine is capable of towing 8800, but we all know that we will generally run out of carrying capacity well before we run out of towing capacity with these trucks. That being said, I was still amazed at how well the truck did on this trip. Yeah it sucked gas, but that is to be expected. If I did this all the time I would have a diesel, but my truck brand new was UNDER $30K AFTER I added remote start, tinted the front windows, had the hitch installed, had them put on a hard Mopar folding cover and added the factory trailer brake. UNDER $30K. There was no way I was going anywhere else to find a truck that cheap, and even a cheaper version of a 2500 with a diesel would have been a lot more than that.
As far as the rest of the temps you listed, I was right there with you. These trucks are so much better than they were in previous generations.