I had a 2013 Chevy same set up. I was pulling 5,000 TT and had the bed loaded about 150 lb over rear axle spec. It pulled good and would get up and go on the expressway but I wouldn't want to tow more. Towing 6,000 might be ok for me but I liked it at 5,000. It also matters if you are only going 50 miles to local stuff.
Big difference between what they say you can do and what you want to do mile after mile. There is a guy sitting next to us right now pulling a Cougar FW with that same 1/2 ton truck. We are in the Black Hills!!!!