my guess is the rental shop gave you BAD info, either by accident or on purpose, not all workers are that great at there job or care about customers or the business they work for! Good help is harder to find now than ever!
But either way, finding out spec's isn;'t hard, and towing a machine this size, odds are, will require some add driver's lic credentials than a basic lic's, and finding a dump trailer of the size needed will maybe be harder as well,
Might be better off having one delivered than doing so yourself, as I'd gather most using machines of this weight and size, ain;'t using dump trailers, but deck over trailers, due to more common and easy to find, and just more folks owning them !(or is this way in most places I have been)
so keep that in mind, if your considering renting one, or buying one!