The numbers you need are the ACTUAL weight of the RV (get it weighed), the GVWR (Gross Vehicle Weight Rating) and GCWR (Gross Combined Weight Rating). There is usually a tire placard with this information on the driver door.
Tge GVWR is the most your fully loaded rig can weigh, and knowing the empty wt lets you know how much weight you may add (passengers, clothing, pots and pans, souvenirs)
The GCWR is the most your RV and the Toad and hitch combined, may weigh.
Some folks subtract GVWR from GCWR and think this is the most they can tow. NOT TRUE. Weight allowed but not added to the RV increases towing capacity.
Example: IF GVWR = 20,000 and GCWR = 24,000 AND the RV is loaded to 20,000, then you are limited to 4,000 towed weight.
IF the RV is only loaded to 18,500, then your towed weight can be up to 5,500 (24,000 - 18,500)
The placards are the ultimate authority.