If you have a local clinic that specializes in a spay and neuter program, I would bet money that they would be happy to take your info and find a kitty for you.
I work at an animal birth control clinic and we have at least one adult cat looking for a home every week. Plenty of them have made excellent barn cats for people that come in looking for just that. When the other alternatives for the millions of unwanted cats are TNR (trapped neutered and released back where they were found) or euthanasia, I am happy someone wants to give them a chance indoors or out.
Sure there are risks, but it’s far better than no chance at all. There are not enough homes that can provide what your rescues are requiring. They need to be more realistic.