I have some experience with the Michigan Gray. I was a graduate student at UoM, Ann Arbor and then lived in Ann Arbor, working at GM for a year after graduation.
A backless cat couch so that your cats can sunbathe sounds like a beautiful idea. The front of our home faces West. My youngest daughter’s cat, Camilla, loves curling up on the duvet on my side of the bed to catch the late afternoon sunlight. In the morning, she sits on my daughter’s bedroom window.
I guess you noticed the notch in Alphie ear. He was found as a feral kitten, and we adopted him about three months ago after my wife fell in love with my daughter’s cat. Both Alphie and Camilla were adopted from SAVE, but Camilla had lived at SAVE for about a year before adoption.
Unfortunately, they don’t seem to get along, so we keep them on separate floors. 🤷