I believe you meant to state Upshifting after revving? Paddle shifters only recently have been able to force an upshift depending how they are calibrated where this function is mostly reserved to performance cars. Also if the ECM and TCM is calling for a lower gear, it will be more efficient than lugging so let the truck perform the way is was calibrated to perform.
You did not state the speed you tow at as well where the faster your tow, the more fuel will be required to offset wind resistance. I tow at 62 mph on average as an example. Also winter grade fuel and cold conditions will result in the 02 system biasing rich since oxygenated fuel will burn leaner to aid in cold starts. Cold air increases wind resistance and cold fluids increased friction. So cold starts will destroy your average economy as posted on the DIC so reset this once warmed up and on the road to get a better reading on a longer trip. Or better yet, hand calculate the fuel economy but be prepared it may be worse. Final drive is another factor.

There is one more that you may want to try. Before your next trip, run the tank as low as possible and then fill up with 89 octane fuel or 2 points higher than recommended. Read your owners manual on the recommended fuel and what is recommended for towing. Most will not try a higher octane fuel where most of the time its not needed but if there is variation in engine build or a lack luster calibration, the math may prove that a higher octane fuel will save you money over regular while towing for the reasons stated. Use tow haul as well but keep in mind, this will hold shift points longer. Not an issue.

So after stating all this stuff, 10 mpg is not far off but if you slow down, try the higher octane fuel you may pick up 1-2 mpg. Otherwise fuel economy will return in warmer weather on summer fuel and with warm fluids.

Jim

My 2021 Ram 5.7 gas routinely touches 5k rpm when pulling hard, as in getting on the interstate highway, or pulling up a grade. I don't worry about this, because this engine is designed for such operation. I say "touches" 5k rpm, because it doesn't stay there for very long. I would agree that sustained operation of your motor at or above 5k rpm would probably not be a good idea. Won't hurt the motor, but will probably increase the wear and tear factors. In fact, many people believe that getting the motor "up there" now and again is good for it. Normal operation not pulling a trailer or a load, 5k rpm is hard to get to without breaking the law.

As for fuel mileage, we don't worry much about that either. We get around 10 mpg pulling the trailer, and closer to 18 mpg without the trailer. That's the cost of the big vehicle and the work that it does. If we want better efficiency we use our Chevy Volt which hardly ever uses any gasoline whatever, and gets almost 40 mpg when it does. But the Volt won't pull a trailer. Therefore...

Those with a scan tool that can see if the system is in open loop can slow down to just the point where they are cruising in closed loop fuel control.

This thread is drifting all over the place...hopefully the OP doesn't mind. GDPadventures

Jim, I know you're a GM guy but any idea what PID and signal I'd monitor on my Ford to see what you're writing about? I understand (conceptually) your comment, but no idea of how to actually view/monitor. I do have a scan tool and ForScan Lite on my phone.

Just as another data point, after towing several spring/fall trips back and forth from Canada to Florida, with the Ecoboost gasoline engine (always on premium fuel when towing), the fuel consumption was always considerably greater at the cold end of the trip than at the warm end.

Rob