Matt, I’m no expert but from what I’ve learned they are opportunistic feeders. I once watched a show where a guy took rotting kelp from the beach containing maggots, and threw large clumps into the sea. The maggots would apparently float, the kelp would sink and the mullet would take his maggot-imitation off the surface.
Another common method for mullet is to groundbait your mark 3 or 4 days in succession, then fish using the same bait. If that’s not an option for you, try carp tactics with method feeders and ground bait - the smell of the ground bait may pull them to your mark, and my guess is they’d then take the maggots within the ground bait.
Don’t know about corn for mullet, but again they are known to be opportunistic.
However bread is a known winner with mullet, so if you’re after them id strongly suggest that.
I’ve personally been spicing up my bread hook baits with lug worm oil, and I do believe it has attracted larger mullet than straight bread, especially in the low-clarity water I fish. My belief is that in such conditions, given that bread isn’t exactly a smelly bait, you’re pretty much waiting for a fish to pass near your bait and see it, where as with some smelly oil your area of effect will be much increased to draw them within sight of your hook bait.