Its real simple. Buy a truck capable of towing your unit, while keeping ALL the #s within the manufacture's ratings. Or but a camper light enough to be within ALL your trucks towing capacity #s. As mentioned, you can not simply bolt on more capacity.
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS