Since I was posting this bike elsewhere on the forum, I'm dropping this pic into the mix. Contrary to recommendations thus far, this lad appears to have a rear disc that's substantially larger than the front. And unless one of us is conversant in Chinese, we'll never know how it worked.
I'm not wild about his brake line routing. And we're going to agree there's another stay on the backside of the shock mount that's simply not visible in this picture.