Many of us go by GAWR, tire and rims. We have been over on GVWR on every camper combo we have owned in 25 years but under on axle, tire and rim. We have never had any weight related breakdown, accident or issue, not even a flat tire and we have driven a lot of miles. That is just my experience and not recommending anything to anyone. Everyone has to make their own decisions and a lot of factors go into safety. I see guys pushing 80 mph with their 2500's and huge 5th wheels all the time. That scenario scares me a lot more than my TC poking along the slow lane at 60.
GVWR to a large extent is a licensing number. I believe the manufacturers don't want to risk sales by increasing these numbers as license and insurance number go up as well. That's why Ford and Ram cap out at the exact same GVWR in their 3500 duallys Certainly one truck or the other could go above 14k, even a little bit. Look at the fight for TQ and HP. The GVWR bragging rights seem to take a backseat to cost of ownership.