Seems like I remember reading that although your first engine was pulled because of the coolant/cooling issue, that further inspection revealed the bearings in general were all but toast with one or more partially spun?Ram kept the same radiator for the 2020 plus but raised the max tow rating by several thousand pounds while still meeting the same J2807 specs. They did so by relocating the intercooler away from in front of the radiator for more fresh air flow and less heat soak. The limited cool air cannot push the hot air out of most of the fins except for if and what the fans are able to suck out and through. Even then its heat soaked air from the intercooler. It would be interesting to see how Ram's new truck with otherwise same configuration would do in this same comparison.
This is not to say cost and ease of changes made that you went the wrong route vs trying to copy what Ram did or even that you would necessarily get better results from what Ram did. I know Ford did it with the EB and Buick did it with the old Grand National years ago with great results but those are apples and oranges.
Last certainly there is longevity in keeping the coolant temps down even if oil temps are normally the first to cause a derate. Similar to you I generally tow a little less weight but with a little more drag. My first engine was replaced due to a pushed head gasket IE a cooling issue at 371k miles. This I believe was spurred by a leaking EGR cooler that had it run low on coolant. Still a better cooling system may have made a significant difference in its longevity. The second cracked a head at 423k miles. This engine was never overheated or ran into coolant derate. It did however spend some time at 240 - 242 even if it was not often or for very long. Jame's engine is down but perhaps not out with cooling issues at 452K miles. IE all three engines cooling and not bearing failures.