If your vet thinks the cat’s injury can be rehabbed and the cat is not so feral it will be impossible to care for, I recommend a dog crate for rehab care. Drape with a blanket and offer a box with one side cut off to hide in, room for small litterbox, food and water, not so big you can’t access him.

Talked with the neighbor. He’s part of a 4 cat family group with his mother and younger siblings. She’s been trying to trap for a while, but we’re going to make sure she doesn’t feed them Saturday morning and we’ll try to catch Saturday and Sunday.

Second the dog crate. I use one to tame feral kittens. I put it in the living room and let them watch the complete and utter lack of bad things happening to kitties for a while. It helps.