Upgrade towing capacity from 3,500 to 5,000 on Class C RV?
My 2001 Fleetwood Jamboree Class C, Chevy 3500 chassis (454) has a 3,500 rated towing capacity. Class IV hitch. Any suggestions to up the capacity to 5,000? For reference, I tow an '03 focus on a dolly which net to 3,300 lbs. RV fully loaded with gear, passengers, gas and water weighs 11,000. Max GCWR is 15,800 which means I have another 1,300 to spare, for 4,800 total. My goal is just to add a bit more towing weight margin. Perhaps the lower tow rating than some other brands are due to the strength of the frame extension?
History: '08 View, '05 Chinook, '01 Jamboree 24D, '78 Apache Popup, 81 Komfort Tlr,
84 Mazda B2000 'w canopy,
Tent from wedding shower in '96