Just an FYI, we're talking about a motorhome here. So breaking the axles and frame are not really something we see...even with overloaded units. Stopping is the main criteria for weight.
When Ford went from 20,000 lbs combined weight to 22,000 lbs combined...the difference was larger brakes and sway bar.
Towing does matter a bit. On a Class C with a 7500 lbs hitch you can tow the car and load the car or truck up with cargo. OP does not two, so it might not be an issue.
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