disc would not be visible from the back. A 172 with the high wing
makes stumbling into the prop while exiting the plane fairly easy. At
least easier than a low wing.

Say What???

You climb out of a 172 and the door is between you and the whirly thing.
Close the door and the wing strut is between you and the whirly thing. You
are talking about the "Cessna 172," right? You couldn't "stumble into the
prop while exiting" even if you were totally s###-faced, and three times
over the legal limit.