If it's good enough for Bluebird, it's good enough for me! Found this for sale on Facebook.
This makes me feel a little bit better about potentially putting storage bins or even a well-armored mini split behind the rear wheels. I know that inclines are a big deal, so I don't think I'd plan behind-the-wheel stuff if I didn't have to, but it's nice to know that it's literally a factory option, so it is *possible*.