It's not your hip width, it's your ischial width - those pointy sitbones down under. Get a B67 or the new unsprung B68 if you're afraid of a few ounces. Most humans seem to have an area about as big around as a quarter or a fifty-cent piece that surrounds the ischials as padding. The most comfortable fit will have those pads
inside the steel frame that runs around the rear of the saddle. You can't form steel, just the leather.
This is a B67:
