That's a lot of trailer. Could you provide more information on your GMC. The information on the door sticker would help (take a photo), especially cargo capacity and GCVWR. Rear axle capacity is also important..The reason I ask is hitch weight could be an issue when you have a pin weight of 2600. The real pin weight is probably closer to 3000lbs. Others will be along that know more than me. And welcome to the forum.

On edit - now that you have the sticker posted, I hate to give the bad news, You don't have enough truck for the trailer your getting and there is no way around it. The GD pin weight is the dry pin weight and not loaded. Maybe someone will have a solution. Don't forget the cargo capacity includes you, passengers and gear in the truck plus the hitch. It may not include fuel either but I am not up with how Chevy rates theirs. You could easily be over max payload by 750 lbs or more and your pin weight max by even more.which puts you over your rear axle capacity too. Not good Remember the GD pin weight does not include gear, water, propane, fuel, food, ATV's etc. Although weight in the garage could help reduce some of the pin weight. FYI the goose neck pin weight is same as 5th wheel pin weight - it's the factory hitch capacity.

Sorry
Keith

I read that sticker to be a max pin weight for fifth wheel or goosneck to be 2,775 pounds. I would say you will be likely to be way over that, especially if you go with a slider hitch. The Andersen will save you the most weight, but you will need to be comfortable with the hitch. I towed with one for fifteen thousand miles with no issue, but its an individual choice. Its main advantages are you can move the pivot point back a bit to give you more cab clearance, or forward to give you more tailgate clearance, and obviously the weight savings. I only gave mine up because I moved to a long bed, so went to a GooseBox so I would not have to store the hitch and would get some bed space back. I really think with that size trailer (and most toy hauler fifth wheels honestly) you will be well into dually territory.

I am guessing that's a 2500? I have the 320G (shorter version) any my pin weight is 320 lbs heavier than literature states. 2620 lbs. ready to camp with no toys. Hitch gets lighter when I load the trailer though. Not sure what the 350 is, but I imagine it will be closer to 3000K lbs since it's longer.

I sold my Ram 2500 with airbags and have a 3500 on order because it's just too much payload for the Ram setup. Maybe the GMC will be better since it has leafs on the 2500. I run a Reese Goosebox with a shortbed ram. It's 4" shorter than the Chevy shortbed. I have not had any clearance issues due to the design of the 320 front cap. I assume the 350 would be the same cap, plus you have 4" longer bed so likely more clearance than my truck. IMO the design of the newer campers eliminate the need for slider hitch if you are careful. I see people cry they can't "jackknife" their 5th wheels on shortbed trucks or get to 90 degrees. I have never been in a situation where I need to get that much angle and it's not good for the axles to twist that much anyways.

With that said, on my 3500 order I did go with the 8' bed for peace of mind and it comes with a larger tank so it was a no brainer. I am not looking forward to the decrease in turning radius though.

RoyB, thanks for the info. I have airlift Airbags installed on my 2500 GMC. The advertised tongue weight is 2600 lbs. My RZR or Harley or both
will always be in the back

First rule of fifth wheel shopping is to take the weights in the brochures and throw them out lol. With a GVWR above 16,000 pounds I would plan for a pin weight of at least 3,000 pounds. This math gets a bit fuzzy for the toy haulers because the weight in the garage can change it some, but I'd still expect it to be higher than the brochure weight. All that said given you'll be over the recommended hitch weight of your truck I'd go with the lightest hitch you're comfortable with.

We're running the 3740BH - brochure is 13,884 empty, GVWR 16,800, Hitch 2900 pulling it with a 2019 Chevy 3500HD short bed SRW.
The 350G lists 12,950 empty, GVWR 16,800, Hitch 2600.
I know the 2020 Chevy's are supposed to be capable of more, but think you might be pushing the limits a bit far with a 2500.
That said, you'll love how the Duramax/Allison package performs if you don't have experience with them - I've run Ford, Dodge, and now Chevy and really like how the Chevy performs. The exhaust brake on long downhills is amazing - hardly have to touch the brakes, uphill at 55-60 mph on almost any grade without much issue.
(Both Ford & Dodge have strong points as well - this is more of whether you prefer red, blue, or green for your truck color)

We're staying under the max trailer weight but consistently running 3150-3300 on the hitch.
Have the airbags and am staying less than 200 lbs over on the truck rear axle/payload rating with the added hitch weight and 12,000 - 12,500 on the trailer axles so overall weight is doing good and I like how it tows.
We just came south on I-5 from Oregon to California and the mountain passes made me happy we have reserve towing capacity because it's not so much when things are going good that it matters - it's more when things go sideways that it will count.

Couple of BOLD LETTER NOTES:
The puck system is great.... BUT.... watch out for the puck system hardware ratings!
If you're not careful, you'll get a hitch rated for pulling 20,000 lbs - but the puck system hardware will be rated for less - read the fine print?

From what I've been told the 2020 Chevy puck system is completely different spacing than 2019 & older - but if you're buying new this shouldn't be an issue.

Opted for the bigger Superglide hitch as it's made in America, locally several reputable shops that specialize in hitches spoke very well of the company, and we may at some point take the RV to Mexico where we have property which will require navigating some pretty tight areas. I really like how it's working so far and having it automatically slide is pretty nice. Also like that both the hitch & puck system parts are rated for more than what we're towing. (but definitely need help putting it in or pulling it out - working on a solution for this)

Oh, and keep in mind they put a horrible mattress in RV's so you'll want to change it out for a decent memory foam one which will add a bit of weight (about what we're over on hitch!) - it's really surprising how quickly weight builds up.
We run with no water, and both the black & gray are empty or close to it as we typically go from RV park to RV park when traveling.

That's my 2 cents?
Chris