Truck

Nope! Depending on configuration you could be lucky to have a honest cargo carrying capacity around 1800 pounds. My 04 D/A ext cab 4X4 loaded ready to travel scaled right at 7500 pounds, so I do know what Im talking about.

Did your truck scale at 5090 pounds? That seems too light for a diesel.

Look inside the glove compartment and you should see a sticker showing the load capacity of your truck based on its configuration. A much better starting point than the door pillar sticker.

I think the best comparison is rear axle rating v/s what empty truck puts there.
90 to 100% of camper weight will go there.
Why worry about front?

If it's a 2500, no.

Advertised curb weight is the lightest configuration available. Weigh your truck to find out the available payload.

Then you will need to allow 500 pounds for stuff going in the camper. Then figure out the wet weight of the camper you look at. Finally figure a few hundred pounds for options that aren't considered in the dry weight of the camper. Oh, don't forget about figuring any other people or pets you are carrying.

So in reality, even if your truck only weighs 5,090, you would really be wanting a camper with a listed dry weight of 3,000 pounds.

Your math is right but as kohldad explained, it get's more complicated than that.
Weight the truck at a quarry, landfill, scrap yard, feedmill, or truck stop. Try to have it full of fuel and any passengers and pets that you will take with you camping. Subtract the scale number from the 9,200 GVWR and then you know what else you can add.
Going beyond the GVWR is quite common when hauling a TC. For better or worse I'd be 75% of trucks hauling TCs are over their GVWR. It's quite common to go by the rear axle weight rating (RAWR). So, when you weigh the truck get separate axle weights. Subtract the rear axle weight from the RAWR and most people would say you can haul that much. It may or may not be much different from using the GVWR.
After that, you can get into a whole discussion of how the tires really set the RAWR and if you upgrade the tires and possible even wheels then you can haul much more weight. This typically leads to air bags or helper springs on the rear, heavier duty shocks, anti-sway bars, etc.
I've hauled my TC on a truck with a GVWR of 9,900 and the rig scaled at 11,150. I currently haul it on a truck with a GVWR of 11,400 and the rig scales at 13,100. I've got thousands of trouble free miles with both trucks.

Is that published curb weight or measured at a scale weight with you in it and a tank of fuel?

It sounds way too low...

That was in a Chevy web site, all I'm trying to find out if my truck will haul it safely. I'm willing to do the airbags and better rated tires. I know I will be over but will it still be safe is what I need t know. I currently haul a 40 foot 5er with it so I know how to drive safely was an over the road trucker for a bit.is my truck big enough and will it be safe enough.

NO! Tires, wheels, springs, air bags, none of it will alter or increase the federally mandated GVWR rating that GM placed on the vehicle. Can you spend thousands and carry the load? It can be done, but is it worth it at the end of the day as far as safety, comfort, long term durability on a truck that is already 16 years old? Not in my book, but you have to make that decision, not me.