Tiny margin between VFR cruise and over Class C?
I had a similar situation flying over the Class C at Albuquerque New Mexico.  Albuquerque's Class C goes up to 9,400 and I was flying VFR at 9,500.  In this case I was using flight following going from Las Cruces NM to Santa Fe NM and was handed off to Albuquerque Approach.  Albuquerque Approach simply told me to notify them if I needed to make any altitude changes to remain VFR.

I think most pilots would simply call Approach in this situation and let them know they are flying over their airspace.  You would need to know the correct altimeter setting anyway to make sure you are at the right altitude.