Toyo 285 75 18 MTs are rated for 4080lbs but they are 35" tires which would likely not fit the front of your Chevy without trimming even with a leveling kit.
Seems the closer to stock sizes are rated less, but look at Toyo And Nitto. They typically have the highest load ratings for light truck tires.
I have Toyo MTs on mine rated at 3970 and they handle my heavy @ss camper well with little to no sidewall flex.
Being mudders and since I had them siped as well they have not lasted very long. I got 20-25k mi on them now with about 5k hauling the camper and they are about 75% worn. I'm sure that would have been better if they weren't siped.