I found this kind of interesting, so I checked pretty thoroughly into it.
That Chevy 1500HD is literally a rebadged light duty 2500.
Thrre's nothing half-ton about it. It is the 2500 frame, it's got the 6.0, it has the heavy duty 4L80e, its got the big brakes, it's not a beefed or modified 1500, it IS a 2500, with 1500 emblems.
Why? Becatse Ford offered up their F150 crew cab and this was the easy instant answer.
I think this setup is going to work fine with a 20' enclosed trailer. It isn't going to break.
If you're worried about the semi-floating rear axle you can swap it out for the full floater.
The brochure-bible guys say there is nothing you can ever do to increase your gross weight rating... so even if you do install the same stuff the HD truck has, you're still limited by.... uh... a sticker and other imaginary things no one can name.
Or just take the 1500 badges off. They were nothing but a marketing trick anyway.