Right on, Corn Crazy. That's the way to go. They’re pretty cheap in bulk too. But I'd advise buying a smaller amount if you can. Something you think you will go through in maybe 3 months. If you keep them packed well, they last pretty good in a freezer. I've got 4 hoppers left that where I split a bag with Kellum (another member), I think we got them 6+ months ago. They are not in as great a shape as when they were new. Not bad or anything, but next time I am going to try for a smaller quantity.
I had an Indigo Snake for eleven years when I was younger. I had gotten it to eat like ball park or whatever hot dogs, which it primarily ate for many years with no ill effects. I would let them warm up to room temp, but this is the kicker. I put vitamin and calcium tablets into the 'dogs. Alternated vitamin and calcium every other feeding. I also supplemented the diet with frogs and toads, which Indigo snakes are fond of. Very rarely a mouse. Today, I would recommend you stick to frozen rodents though. Although it would probably be good to throw in a few different items from time to time if you can, I think corns sometimes eat chicks, small birds, lizards when the snakes are young, birds probably eaten by older snakes in the wild. I also know they steal eggs from my friend's chicken coop. If you ever try eggs though, probably best to get fresh eggs, not store brand I think.
Feeding your snake smaller items than it CAN eat will not be bad at all. More smaller meals is OK. Once you get up to hoppers, they pretty much have all the stuff a snake needs, I think (if I'm wrong let me know) but you still might look into vitamin supplements for trace minerals and nutrients. I think there is liquid vites you can paint on the mouse. I don't think much is known about the finer workings of snakes, how their electrolytes and hormones work and so forth. In the wild they would get extra nutrients from what their prey had eaten or was "gut loaded" with. Check out what your rodent supplier feeds their product on.