Max Load?

Hey guys. I was just wondering how much i could safely tow with my '11 2500HD. (Crew Cab, Short Box). It would be a gooseneck, probably 30 or 35 feet. Could it safely pull 20000 pounds through the mountains, for hours on end? It would be in winter, and our Canadian winters are cold so overheating shouldn't be a problem. And if i was pulled over, i'd be parked until i could split my load with someone i presume?

Thanks guys.