I cannot see that this will be feasible. In all likelyhood, you are not next door to me, so I can't help, but if you were I would just say I can trade them for a couple of layers or started pullets, because I have more than I need. I raised Cornish Xs before and a few got a bit too old and I started calling them heartattack chickens.
It seems cruel to keep them in some ways. They just eat themselves half way to death. They are always famished. You can put them on a diet, but you are fighting what they were bred for.
You can probably sell them to someone from an Asian or Mexican background. They frequent my house, looking for fresh meat. That would seem better than trying to keep it alive and failing........or even succeeding for a while, but with so much trouble.
This particular breed cannot forage about a yard as well as other breeds due to leg problems and heart problems. Therefore, they won't even be able to protect themselves from preditors and run for cover if needed. They were created to get big fast and feed us.
I do wish you luck with this venture, but I can't see it as being anything promising.