Since you've got a representative sample of all 3 Gustin denim cuts, it would be awesome if you could post fit-pics ... I promise not to mention jeggings or bicycle pants in any of my resulting comments
The downside to tapering just the inseam is that it alters the drape of the leg. To counteract the imbalance, denim tailors (eg. Railcar Fine Goods) will go the extra step and also alter the selfedge side.Some companies such as Iron Heart will even "sacrifice" the selvedge line on some of their tapered models in order attain the cut that they desire.
I'm a 8.5D on the Brannock (8D Barrie last) and bought the Ranger Moc in 9 medium after trying both the 8 and 8.5 sizes. I simply need the added width of the 9 ... I have as much empty toe space as you.