Yep, a little more homework is required. Read all you can on trailer weights, capacities, etc. Same for truck weights and capacities.
That trailer is too much for that truck.
Is the cargo capacity you quoted from the door jamb sticker or a brochure? Every truck has its own cargo capacity depending on options.
There is also a sticker on trailers giving its weight leaving the factory.
Most RV salespeople don’t know squat about weights and don’t care. One guy with “25 years experience” told me that a WDH makes tongue weight just “disappear”.