GVWR is not your tow rating. It is the maximum weight rating of the vehicle itself, plus cargo in the vehicle (like passengers). Your curb weight is 4890. Gives you a cargo weight of 1510. Subtract a full load of fuel and two adults, and you get to that 1/2 ton naming convention.
The tow rating is in the manual, or you can find online. The number I posted was from a quick Google search. The rating is based on more than the engine power and suspension. Frame construction and brakes are a big pat of it. The point isn't weather you can get the load moving, but if you can stop before running over a bus full of nuns.
Sorry, I know. I just tow my 6000 lb junk around pretty regularly, so try to be careful. I've also seen some pretty sketchy loads.