Don't overlook a live shrimp (or even a realistic plastic shrimp...DOA gets our vote!) as a great option while fishing around mullet schools for a number of reasons.
1. Snook, Tarpon, Redfish, and other gamefish are LAZY and never turn down an easy meal! They may not be hungry (or they may be tired of eating mullet), but seldom will they skip a chance to slurp up an easy meal. A shrimp ticking along under a mullet school is easy pickings.
2. Mullet schools (especially big black and silver mullet schools) provide great protection for gamefish from predators like porpoises and sharks. Spotted seatrout, smaller redfish, snook, and others will mix themselves in with mullet schools a lot of time for protection, not to eat the mullet. A shrimp though seldom gets turned down.