The payload indicated on the placard of your driver's side door jamb is, in fact, the payload specific to your vehicle. Exceeding the specified limit by one pound does not imply that your vehicle will detonate; nevertheless, it does indicate the maximum weight designated by the manufacturer for your particular car.
Not vehicles akin to yours.
Your vehicle precisely.
While you should not concern yourself with that figure, your inquiry suggests an interest in it. In legal matters in many regions of the US, the law and insurance companies would be concerned if you experience an accident.
Consequently, we shall presume that you do not intend to surpass that figure.
Subsequently, employing a weight distributing hitch with any unibody vehicle is generally criticised, owing to the underlying mechanics involved, which transmit forces throughout the vehicle's frame.
In a conventional truck, this occurs via a designated frame, unlike in a unibody vehicle. Notwithstanding the assertions of "the representative at Mazda," this practice is typically disapproved of.
Your vehicle will not detonate if you proceed.
More akin to incremental and meticulous adjustments over numerous tens of thousands of miles.
Ultimately, for camper trailers, the weight metric of primary relevance is the GVWR. This represents the maximum weight the caravan can accommodate, commonly utilised as a standard measure, as campers often underestimate the weight of their belongings and tend to overpack on each journey. By utilising this figure and estimating that 10 to 15% will constitute your hitch weight, you will possess ample margin for error, as well as the capacity to transport all your comforts.