If you want to be 'safe' go with a dually.
Check the Ford payload tables (goggle for them) and u can see the differences.
I have a 3100 lb Citation. Love it. It weighs 3100 lbs on the sticker. If u read the fine print it weighs more than that because of the options which are excluded.
The best test is to go to a weigh scale. They tell no lies.
Ford does not warranty non 'camper' option trucks when they are carrying a rig. The dealership salesman is wrong. It is in his interest to promote Ford.
However Ford would need to know about your transgression.
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