It almost seems harder for those who have already made an issue of food. My mom followed Slatter-like methods as long as I can remember with all three of us: one meal for lunch and dinner (with a bare handful of exceptions for when one or more of us really, really hated something), apples/fruit or vegetables as snacks whenever we wanted, no fuss or force feeding. We all went through a time when given the choice, we'd take pasta and cheese, hot dogs, pizza, bread, potatoes, etc but during the same time, we were perfectly good with and rather enjoyed tomatoes, cucumbers, bell peppers, broccoli, peas, carrots, citrus, basically all berries, and watermelon, probably among other things. It didn't seem to really occur to me or my sisters to refuse to eat to get a diet of straight pizza; one dinner was just how things WERE. But I think if a kid has already seen victory, it might become exponentially harder, because they know the current system isn't the only way things could be.
Keep fighting the good fight! I think in your shoes I might plan a menu with corn dogs every 2-3 days (to assuage your worries that he eat sometimes, and also show that everyone can have their favorite food sometimes), but I'd only let him have 1. And it's not frugal, but I'd temporarily buy the small packages, then if he wants seconds, "sorry, there's no more!" or "those are for Thursday!" depending on the pkg size. But not like there are 30 more there for an indeterminate "later". And of course, serve with a side of vegetable.
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