The length to wheelbase is just a guideline. Units that do not meet this requirement tend to be more of a problem with handling than units that have a better ratio. But they don't all fit the rule.
Some chassis do better than other chassis. If you are serious about a coach, get it out for an extended drive. Get it on the highway at highway speeds, some smaller roads and city streets to see how it handles. You do have to remember that it is unloaded at this point and can change once loaded or overloaded. Make sure the tires are aired to the pressure recommended by the manufacturer.
I would get the rig weighed to see just how much real load capacity you have remaining. There were class C's built that with a driver and passenger in the front, the front axle was over rating.
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