It’s simple, a class WITHIN a class. If you want to keep racing Rotax, pool together enough racers and ask your promoter/series/club to create a class within the Senior Max category for drivers over 190lbs. Karting is mostly racing for a trophy, if you can get enough racers together, maybe they will offer up a first place trophy.
Otherwise, continue to work hard and improve as a driver against the Senior drivers. If you can get to within 10 to 15lbs., it is realistic to be competitive. Many drivers have done diets and training to lose weight for racing.