first, payload capacity is more important than towing capacity because almost all tow vehicles will run out of payload before getting near the towing capacity.
second, payload capacity(it's on the yellow/white door sticker. usually says Tires and Loading-Occupants and Cargo should not exceed xxxxlbs)is what that particular vehicle is rated to haul weight-wise. loaded tongue weight and the WDH weight have fit in that number.
the driver is considered an occupant. it also is figured a full fuel tank.
third, towing capacity is what the max amount the vehicle can pull. that number includes a full tank of fuel and a 150lb driver. anything other than that in the vehicle, lowers the towing capacity by its weight.
i've never heard of any such type of database. you have to estimate the weight of passengers and cargo in your Explorer and how much weight you'll put in the trailer and find trailers that will handle that.
you will be limited to trailers under 21'. NEVER use fictional "dry" weights. generally, using the trailer's GVWR will work, since 21' and under trailers will weigh close to their GVWR when loaded for camping.