Totally get it, our animal shelters are overwhelmed as well.... We try to keep our male ferals at least overnight to assure the anethestic has worn off totally, so they can get away from predators....the females we hold for 5-7 days to insure proper healing as their surgery is more invasive. We have a double decker cage that we keep the ones we are releasing back to nature in and that is in our garage. That way we have a litter box for them and can monitor their feeding habits. The kitties we catch young enough to tenderize (rehabilitate) we have a room in our basement that we move them to and after worming and flea treatment we let them have the run of the room....it has a screen door on the room so we can monitor him/her and they can hear us easily to acclimate them to human noises....also our resident kitties can go down and visit with them without any danger of anyone getting hurt.... Hope this was helpful.......