Stability wise a 28 to 40 foot fifth wheel with a dually Long bed crew cab truck will be the most stable without question.
The long wheelbase of the truck makes for stability and the dual wheels on the rear absolutely make it more stable-- and just the way it's mounted ,the fifth wheels have best stability.--if it wasn't the best setup then --Why is every single commercial tractor-trailer a fifth wheel and not a tow behind...????
(And before someone says" well the ones on Three trailers are pull behind"..-- no they're not-- they are fifth wheel on a dolly.:W