When we would tow the 19 with the GC I didn't use extra mirrors except for the little 2 inch square stick-on on the stock mirrors to give me the wide angle view. With the 21 the extra two inches I felt was just enough to add on the clip on mirrors to each side. They allow me a better view directly behind and also the trailer tires.
We recently purchased a 2015 Jeep Grand Cherokee with the pentastar V-6 engine to tow a 17B we will be picking up at the end of Sept.
I was wondering if you use or see the need for towing mirrors? If so, what type do you have?
On the Jeep we used the Grand Aero mirrors, they worked really well and fit existing mirrors. We needed them for the 19 for sure.