Force everyone to wear the same shoe. All you get is a size choice (in both length and width). That's how they solved it for windsurfing - just forced everyone

Force everyone to wear the same shoe. All you get is a size choice (in both length and width). That's how they solved it for windsurfing - just forced everyone to ride the same exact gear, no matter the weight of the athlete or how strong the wind is, even though normally these two factors are absolutely defining when you select which sail/board to ride. The rule “must not be constructed so as to give an athlete any unfair additional assistance, including by the incorporation of any technology which will give the wearer any unfair advantage.” doesn't make any sense. Of course shoes are slightly different, and so some are bound to be better than others. It's an unsolvable problem, unless you standardize the gear.