No prep, just strip the meat off the carcass, and usually whizz the leg bones in half or thirds with a saw while they are frozen, to save some space.
Green bone does not splinter like a cooked one will, supposedly. The bigger dogs would go through a rib bone faster than a kid can go through a freezie on a hot day, and even the Iggie would make a rib bone vanish in a few minutes.
I have done turkey carcasses, as well as frozen boxes of chicken backs and necks, as you describe, and a regular countertop meat grinder works well enough for that. A scoop onto the food bowl usually pretty much caused a feeding frenzy! LOL!