In years past I’ve tried to let them dry out for dry beans but the season in Nova Scotia is just a bit too short for them to get fully mature, I’ve even tried shelling them and then drying them by fan like you said and they just get moldy unfortunately. As for the toughness, I have experienced this, but my dad found a very strange tool in the thrift store and gave it to me me because he knows I like old hand tools and I figured out it is a French green bean slicer! It cuts thin diagonal slices of bean which when fried negates the toughness! If you see something like this buy it!