@KRack I STRONGLY suggest you don't do this. I understand you are going to try it anyways. I could waste my time explaining why, even if you do things perfectly, you will end up with nothing better than educated guesswork (still a fair site better than uneducated guesswork, but definitely lacking in certainty). I could explain how, for the very vast majority of people who don't enjoy commercial advantages of scale and efficiency (and have facilites to store crops to last the year), the end result is far more expensive. Or that the typical person has not the acreage, the climate, the equipment, to grow all the components of a nutritionally complete feed on their own property. I might even waste my time explaining what I do to bend the cost curve somewhat.
But I'm not feeling that charitable.
Instead, I'll offer this. Science tells us - because its one of the best researched subjects on the planet* - what a chicken needs for optimum production. They are your birds, you can do with them what you will. If you don't want optimum production, you needn't feed them in a way that makes that production possible. If you are willing to shorten the planned lifespan of your flock, you can cut a lot of corners by shortening the timespan in which poor nutrition can lead to negative health outcomes - that's part of how CornishX (together with a hefty dose of selective genetic breeding) puts a bird of supermarket weight in the display in just 6-8 weeks)
In everything there are tradeoffs. Making intelligent tradeoffs, a balancing of understood risks and rewards, is - I contend - not "overthinking" a thing.
*Why is it so well researched? Because history tells us that starving populations tend to overthrow - or attempt to overthrow - their governments, and there are a lot of countries on the planet who would rather that not happen to them. and on the flip side, there are a lot of profit oriented companies interested in the cheapest costs of production. How many widgets for how much money?
P.S. FWIW I know what the optimum feed is for my birds, I've done a lot of reading. I CHOOSE not to feed them in that fashion. I also eat most of them before they hit two years of age, and many by 18 weeks.