Already happening in Los Angeles, but you're right about the NIMBYs. Though a thought does occur to me with regards to this, why not use abandoned malls. Most of the infrastructure is already there and they could probable fit a couple of housing units where a single store used to be if you go for that minimalistic style seen in high end Japanese Capsule hotels. Increase that exponentially if it has what used to be a Sears stores attached to it.

It's been done before, granted that was more for profit rather the to help the homeless.