I pull a 2020 Tare 19'6" with a 2011 Colorado auto and I think it performs very well. The Holden Dealer advised to tow in 3rd but it's revving at 2400+ at an indicated 85Kmh (78/9 on GPS) I tow in top gear and manually change down for up gradients, (2nd gear @ 2500+ up thru Adelaide hills) I think it's a pretty honest vehicle. Have made some mods to help and just put it on Gas over Diesel which should help a lot more.
We have a 2013 LSU 3.0 litre auto and tow a 28 ft 5th wheeler. No trouble at all and are very happy with it. It has excellent fuel economy of 7km per litre when towing, even with full 250litre of water on board!
Yours is the next model which has a bit more power and also a 5 speed auto. The one im looking at is previous model with 4 speed auto, same motor but in yours they changed the inter cooler etc to get more power.
I dont go down to 3rd gear I just use the auto with no trouble - i am towing about 2.5 ton, I usually drive around 85kph and we dont have an extra cooler
the temp never increases always in mid range. We havnt added anything to it and so far tows great.