Laura, you can design for the homeless every time you get involved in the design of a public space. The hardest part is to put yourself in their shoes, and you’re already doing that. Also, you don’t have to actively involve any institution, department, or anyone else in the process if you feel they will impede the the process rather that help/support you/the ’cause’. Each time you make a design decision, you can make a contribution, big or small. There will always be external stress, which is unavoidable, and for various reasons, as it is expected in any project. But there is always the possibility of low key impact. I’m also a MLA second year student , but I’ve been an architect for 9 years now and my favorite thing about this profession (MLA specifically) is the possibilities when it comes to public space and the impact it has in as many areas as we want to include… it is so inclusive in that sense.
I know you were talking about the macro aspect of the issue and how we approach it as a society, but in the mean time, we can do our part, even if small, in our own projects.