Transmission temps lower when towing

Here’s a curious thing I’ve noticed with my truck (2016 ram eco diesel 4x4). Driving regularly unloaded I see transmission temps around 180-190. Multiple times now I’ve noticed that whole towing my 32’ TT (probably 7500 lbs loaded), it stays pretty much constant at 170, even in hills. My only guess is that it’s due to higher fan utilization (I can hear it often while towing) because of higher coolant/oil temps, which is making the transmission cool better. Anyone else experienced this?

For example, Yesterday, I towed my Camper 220 miles, and it was about 50 degrees. Stayed at 170. Today it’s 39, and I hit 185 driving without a trailer or payload.