That is something to consider, with the caveat that not everyone can (comfortably) ride on their pubic rami, either. Going narrower certainly gives one more options in terms of a T-shape.

Even for someone like me who does sit exclusively on the ischial tuberosities in a road position (which is why my soft tissue gets ground to hamburger in a deeper tuck when the rami get closer to the saddle), guidelines aren't commandments. A centimeter on each side to the outside of the outsides, is a necessary margin for tensioned leather saddles, but more of a nuance on monocoque shell saddles. How far are the outsides of your sit bones from the place on them where your weight is typically centered when you're riding straight down the road? How hard do you corner? How domed is the saddle? Do you shift around in the saddle while riding straight down the road?

Spec' at least used to have a 30 day return policy on saddles purchased from their website. So you could certainly try something narrower and see how it works for you.