Thanks for asking. I had posted in my build thread, but forgot to update this thread.
Since starting this thread we’ve taken two trips; one with the stock system, and the second with the new 7 blade fan and a new fan clutch installed.
The first trip, in June, was to Grayson Highlands in SW Virginia. It was a brute of a trip, particularly the last 10 or so miles. Without the new fan, temps got pretty high - 230º or 240º for the coolant, and the trans briefly reached 256º.
In July, once the new fan and clutch were installed, we went to Douthat State Park, near the West Virginia border. Not as steep as Grayson Highlands, but still a pretty good workout for this Suburban. Coolant temps were in the 190º - 205º F range; once or twice getting to 220º, but no higher. Transmission fluid temps were mostly around 180º - 200º, with a high of 210º. The old fan clutch was apparently shot, as the fan was much more noticeable when it came on. Both temperatures were significantly lower than on the previous trip.
I’m now confident that this beast will handle any sort of towing we ask of it.