Four winds went cheap with my 30 foot Hurricane on the F53 V19 engine chassis and put a 3500 lbs hitch onto it. My new car weights about 4000 lbs and I had to find a solution to tow it. I crawled under the motorhome to see what was the reason for the low weight hitch and what could be done to change it, The main reason was how the installed the frame extensions. somehow I got the impression that they decided welding roods were very expensive and they did not weld the gusset plates between the original frame and the extensions all around and to the full length of the plates. I had a certified welder add some more plates and thoroughly weld everything together. I also added a 500 lbs trailer hitch and also had that increased in strength. I bet I could tow now the theoretically possible weight of 10000 lbs without any problem (that is the result of my calculations - I used to be an engineer). However, in my opinion, the main critical fact in towing heavy loads is slowing the unit down.
I would never to anything heavier than 2000 lbs without auxiliary brakes. Many states requiring trailer heavier than 2000/3000 lbs to have their own brakes.
