Having pulled rv trailers from large to small over 100,000 miles in mountains, hills, and flatland I would say based on my experiences that most tow vehicles are somewhat overrated by the manufacturers rather than underrated in regard to their published ratings.
Pulling near the maximum rated load will result in shortened vehicle life and high maintenance requirements on brakes
, transmissions, rear axle
components and oil changes. Even with high level care you will be fortunate not to experience failures if you consistently tow near the published to limits of the tug.
When that adverse situation presents itself, a quick lane change, a panic stop caused by other road fools, you will become rapidly acquainted with the "pucker factor". If you are lucky enough to escape
unharmed and undamaged, I believe you will be quickly evaluating your decision of living on the edge of tow capacity.