I feel that a 1 ton+ (350/450/550) truck is designed to haul it's limit day in and out. Around here with the mining industry you see 1 ton duals loaded with parts and equipment daily, along with 1 ton trucks with bed mount cranes that probably weigh at least a ton by themselves.
We purchased one of our trucks used, by a gentleman that hauled feed from Mt. Airy, NC to WV daily. It's an '04 duramax 1 ton dually w/overload springs and he still had weigh receipts averaging between 3~3.5 tons in the bed. Granted like I said it's got overload springs, but it also has a 7.5x9 aluminum bed. The thing is still a beast and the front end is great, rear end too... Only thing we've done is pads/rotors.