Bedlam; I scale in at 5,490Kg.(12,078 lb.) on the drivers with the camper and boat loaded. Total is 12,836 Kg.(28,239 lb.).
OK so I found a company in Eastern Canada that manufactures a system that bolts right into the spring hangers,
https://www.autoflexsuspensions.com/
Called one of their customers, he says it works just great on their 550. They also have it on some 250’s. About $3000.00 cheaper than Kelderman and a lot less work to install, also includes compressors and controls unlike Kelderman. Called up “Link” they have discontinued there system that looked pretty good.