Riceowl (wacky name but intriguing) I bought a used bike that came with a foldit, and despite my skepticism, it is a reasonably stiff rack---given the number of bolt points and only two vertical supports, it does a great job.
My wife used it with pretty full rear panniers and it performed fine. I checked the bolts regularly, but was good.
It should for your requirements for space saving.

One to consider anyway.