To be absolutely honest, the difference is marginal in most (but not all) cases.
You probably won't even notice any difference in:
wide or baggy garments (like a tunic or pirate blouse)
garments where the shoulder seam extends far down the shoulder (like a kimono or most casual menswear)
garments sewn from stretchy fabric
Puffy sleeves that ...
The obvious solution seems like the best here. Sew it on by hand. This requires basically no sewing experience; if you can sew on a button you can do this.
Don't put the needle through the wire. Rather, put the needle through the fabric from behind, wrap it over the wire, and put it back through the fabric on the other side. This makes a loop of thread over ...
Here's a way to curve the rim on the rubber. Get a scrap wooden board big enough for each sole, and at least as thick as the depth of the curve. Cut out the shape of the sole. Put the desired curve around the edge (could use a router, but probably fast with just a sander). Make the finished form slightly smaller than the sole (by the thickness of the ...