I've read your previous posts, so I know your son is an adult. Young, but still an adult. What is HE doing about recovery planning? If he's in rehab, someone should be available to give him information on sober living, etc. You don't "want" him home, and don't "want" him homeless....but that isn't really in your power to control. When you set the boundary that he can't come home, he needs to pick up from there and find solutions. Otherwise, nothing changes in the end if you still do the work and find the solutions for him. Let him figure it out, let him work with his sponsor or his counselors in rehab to figure it out.
Sorry if this sounds harsh, but I"m hearing you step in to figure out what he does next. It's his journey. Give him the opportunity to decide his future for himself.