For the OP,
What jefe4x4 says here is real. I also have almost identical rig he has and can verify. I have a light Milner on mine, loaded pushing 2200lb with a 4300lb payload.
I have one thing to ad though.
If you think you might tow a trailer while the camper is on, go with the 4.3.
I sometimes tow a 6×12 cargo trailer or a sxs with a 18ft car trailer.
I been up and down the sierras and cascades a number of times and can not even tell I am pulling and hauling. (The Godzilla and that 10 speed trans with tow/haul is great)
Remember tongue weight on trailer is approximately 10% of total trailer weight, you need to know your trailer weight and tongue weight.