I've towed my 21 1/2 ft (total length) Flagstaff 21FBRS with my '16 JGC for about 25,000 miles over the last 5 years. It has the V6, so is rated to tow 6200#. My trailer is just over 5,000# loaded, and it is only me and the DW in the Jeep, and very little more cargo inside. So we hit the scales at 10,200#
I live in AZ, and tow all over the west. Mountains and canyons are not a problem. and wind is very little problem. My Equal-I-Zer is set up very well, so when the wind is bad, like always in New Mexico, I just slow down.
I've had no reliability issues with the Jeep. Also, I think the another poster is mistaken is saying the 2021 JGC is on the Alfa base. That is the 3 row that they call the WL and is a 2022. It is starting to be shipped. But the 2021 is a 2 row, known as the WK2, and is still on the Mercedes platform as it has been since 2013.