Please check if my reasoning is correct.
One problem with using lenses designed for SLR and DSLR cameras with a reversing ring is to be able to control the Iris so you can view and focus wide open and then stop down to shoot. Modern SLR and DSLR lenses have an automatic iris that allows the photographer to do just that - when the lens is mounted on the appropriate camera
However, once the lens is removed from the camera the iris is wide open. There are several fixes to control the problem but, they are a big PITA. What would be nice, for shooting in a reversed lens mode, is a lens that allows the iris to be controlled manually = on or off the camera
Why not use a 35mm film rangefinder camera lens with a reverse adapter. Since the photographer is not viewing the image through the lens of a rangefinder camera, that lens doesn't need to open and close automatically. There are also many rangefinder lenses that are available dirt cheap. The only caveat as I see it, is to get a lens with a filter thread at the front that would fit an available reversing ring
Here is an example of some rangefinder lenses available at quite low prices...
https://www.ebay.com/itm/Jupiter-8-5...gAAOSwrdhalGxn
However, a person would need to ensure thet the lens has filter threads at the front
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