GVWR of a 2009 Dodge Ram 3500 Truck Quad Cab Laramie

My 07, DRW, cummins, Quad cab, 4x4, LB, Laramie had GVWR of 12,200 per door jamb sticker, my 16 (same exact config) is rated at 14,000 GVWR...

3 tons

Same axle and frame as your 04. 2 less rear tires and lighter springs.
If you're intending on going by the rated capacity on the door placard then skip it and get a dually. If you're only concerned with what the truck is capable of, then the axle is good for 10klbs. OE wheels are very conservatively rated at 3500-3600lbs ea and you can get tires up close to 4000lb rating.
Means a total cargo weight of about 4000lbs on the rear axle, with the right suspension for "stability" is good.
If it's a long bed, a shorter camper will likely transfer some to the front axle too.
Gvwr will be the most conservative if you're set on going by the mfgs numbers and you'll get hung up at around 2500lbs even though the truck isn't yet breaking a sweat.

Can the seller give you the information from the door post sticker? You then have it for that particular truck.

Should be 10,500 GVWR. My 07 dually scales 8000,and a GVWR of 11,500. so a SRW should be right around 7700 pounds ready to travel. SIL has an 07 SRW he put a Bigfoot on and he wishes he had a dually.

Go to the RAM BodyBuilder site. You can find all the weights for any year RAM
http://www.rambodybuilder.com/2009/docs/dr/mlup3500.pdf

Idk, but it’ll haul a 4000lb camper just fine with a little suspension help