Some 22s are better than others, and most of the time it's the forward CofG that you will exceed first. Betas are usually ok, Beta IIs you may not have much room to play with. The only way to tell for sure is with that aircraft's weight and balance figures.
A good organisation will maintain a list of aircraft, instructors, and a maximum student weight those instructors can fly with in each aircraft.
If you exceed the limits in the operating handbook, then you are on fairly dodgy ground if something goes wrong, and morally dubious ground even if it doesn't.
