Since you're in CASS, you might be able to pull it off, the odds that the agent will check a reciprocal list in addition to running CASS is probably pretty slim.
However I just checked, and our FOM says that a jumpseater "must have a reciprocal agreement." The fine print is against you.
A better question would be why isn't there a reciprocal agreement? We have several 135 operations on there, AirNet and Key Lime for starters.
Shoot something over to jumpseat @ f9fapa.org. (kill the spaces, obviously) and see if you can get something worked out. The jumpseat committee is very proactive.