Not clear why you think that I have 'tiny feet' - or, in fact, what my (or your) foot size has to do with this.
You are wrong to suggest that "that every guy with big feet looks at" waist width. If they have sense, they consider width at the inserts.
The reason that manufacturers do not list width at the inserts is simply (and obviously) that the width varies along the board/for the different inserts, so that there is no single number.
The approach of taking the average of waist width and of nose/tail width to get a rough estimate for width at the inserts is fine - and is something that I have mentioned on several times before.
If you had normal sized feet you would never have said "Waist width is irrelevant".
But now you are saying waist width is an important part of the equation.
I think you are getting your made up facts confused.