I don't think this is exactly what you're looking for, but I started fostering by working with my local shelter. I completed an application to foster for the organization; although I had a specific dog in mind, it was just a general form with background info about my experience with pets and references. I think there was an opportunity to provide a breed preference, though.
After I had that experience, I was able to use the shelter director and assistant director as references when I wanted to move on to working with rescues both in and out of the area.
Hope this helps somewhat.
Angie and Spirit (8, BC/pyr) & Huckleberry (8, beagle) William (1993-2006), Kate (1995-2008), Johnson (1998?-2011), Odysseus (1996-2012), & Mildred (2002?-2012)