Macro for M/F
When focussed at 1:1 the image circle doubles ....
Are you sure that the actual image circle projected out the back of the lens doubles? I really doubt that. If you were using a large format lens and focusing with a bellows, I'd think you were probably right. But using a 35mm lens with helical focusing and probably intervening baffles, I'm pretty skeptical.
In any case, even if you were willing to live with manual focus, you'd need an adapter with a mechanical actuator for the iris, or else I think you'd be stuck taking (and focusing!) at f/22 or whatever.