IF you are stuck on a 1/2 ton, you want the GM Max Trailering package. The truck should come with the bigger mirrors (as the first clue) and the code NHT on the sticker in the glovebox. I would not try to tow a 30' with a non-NHT GM half ton.
For my 2015 GMC with the above, I have a payload of 2,015 lbs (per the sticker on the door jam) and a max trailer weight of 10,800 (meaningless number from a brochure).
I tow a 33''4" 2010 Cougar 30RKS that has a GVW of 8,200 lbs (and I've scaled it at that loaded). This put me at my maximum payload. I also use a Equal-i-zer 4 pt hitch that does both weight distribution and sway control. I'd recommend this hitch or one like it.
Any more weight and I'd need a 3/4 ton. Interesting that the current version of the trailer has a GVW of 9,500 lbs. I would not tow that with my truck.
Right now, I'd be inclined to wait until the new 3/4 tons come out. the 2020 Sierra/Silverado 2500HD will come with a 6.6L gas motor and close to double the payload of mine. If you don't like them (and I really do like the looks of the GMC) then the price on the 2019's should come down as dealers try to clear them out. Should be mid-June by everything I've read.