Maybe my comments here don’t fit the context, but when I began riding because I have short wide feet, I sought irons that were wider than standard and had to settle for the widest safety stirrups then available, 5-1/4. I spent a lot of time a few years ago looking into irons and widths and recommended foot placement inside-to-outside, and playing with this on my own. Those in every discipline have their own preferences and recommendations, from the late Helen Crabtree in SS, to GM.
What I’ve been able to figure out – and this contradicts my earlier ideas a few years ago --is that wider is not better, that all it accomplishes is potentially to inadvertently screw up left-right weight distribution in each iron which has bad symmetry ripple effects.
There are more important leg considerations and, frankly, the contact of calf with each side of a horse or pony is much more important than any other consideration and that overly wide irons will likely complicate that, all the more so if you don’t have Donald Duck feet like I do.