Should I buy a Class C or not for this specific situation?

If it were me at that price range, I would look for an older high end Class A versus a Class C. A 15 to 20 year old high end Class A will LIKELY have a better exterior than a Class C 10 to 15 years old. A Class A diesel coach has engine and transmissions that are built to last longer than the typical Class C. Obviously there are exceptions to both styles. Just saying don't limit yourself to just Class C in your search.