It is not useful to put an empty weight in a brochure or on a website because the weight of a RV might vary several hundred pounds or more with options. Most motorhome manufacturers have quit trying because buyers would expect a brochure weight and find the delivered weight with options installed to be quite different. That's also why a salesman can't tell you.
For any particular unit, a salesman can go out to the unit and read the weight from the tag. That will be weight as it left the factory with all factory installed equipment.
Some TT manufacturers still put an empty weight in the brochure as a sales tool, but the figure is almost always misleading, because it is often a weight with no optional equipment, not even including the weight of mandatory "option" packages installed on every unit going out to dealers.