Sure...you are over GVWR. By that definition, you are overweight. But I agree that the real question here is can you safely tow this...is the GVWR a real number?
My experience with my new Ford F350 4x4 diesel sclb was enlightening. The GVWR for the truck is 11500, and the yellow stickered payload capacity is somewhere around 3600. So far, so good...but I am right about there with my Heartland Bighorn and two people in the truck. At or slightly over, depending on how I am loaded. Not enough to worry about but all the hype on the capacities of the truck and this is all I get?????
So...I look to the Ford towing guide, which says that my truck configuration has a payload capacity something like 4680...just a tad higher than the 3600 stickered payload (going from memory here) for the 4x4 sclb. Now don't tell me that the Lariat leather seats took up all that capacity. The same tow guide limited fifth wheel weights to 18,000 lbs. (mine is gross rated at 15,500)only because the Ford fifth wheel hitch is the limiting factor....use a higher rated hitch and the numbers go up into the 20,000+ range.
The question becomes...what does all of this seemingly conflicting information mean. The yellow stickered GVWR tells me that I can barely tow this trailer that weighs about 14,500 loaded. The tow guide ratings published by the manufacturer tell another tale.
My opinion, based on calculations and lots of time looking at it was that the GVWR is a registration/taxation construct. Real world numbers are dictated by axle ratings and tire ratings.
Real world test; Hooked up and headed on 8000 mile trip towing through the Colorado Rockies. The payload didn't even make the rear hit the overload springs. I had added Timbren springs and they came into play at the same time as the overload springs....rough roads etc., and barely at that.
My experience confirmed what I thought.....so as others have said, I would look to the tow guide for your year and study the axle, tire and payload capacities.
I'm a pretty conservative guy...but GVWR for me is a nice goal but not a real-world limit. Anybody that says that you are risking your life by being over the GVWR just hasn't looked at the real ratings. Your tires and wheels are the real world limiting factor for you....but I would also add that you are pretty darn close on that rear axle rating and you have a 10 year old truck. I would be more comfortable in a truck with higher ratings.
All the best.