I have a 2020 F350 4X4 SRW with an AF865. It has an 11,300 GVWR, the camper wet is about 4200#. I am over the GVWR by a few hundred pounds, but well within the axle ratings. I changed the tires to 4080# rated Coopers and feel I am good to go.
As everyone has said, drive it first. I have added a Helliwig BigWig sway bar which was a huge improvement, and Firestone air bags to level it to keep the headlights out of others eyes. I am still experimenting, the overloads do not contact the bumpers even with the camper on, so I have added 2" bumpers to get the overloads to work. Taking it out this weekend so we will see.