Most of my rifles are antiques, and have crescent plates. Some of them are pretty aggressive. I have one rifle that has a massive amount of drop AND an aggressive crescent. I'm guessing: a lot of that would be custom tailoring to fit the first owner. Folks were a lot smaller back then.
When I shoulder one, I start with the butt close to my shoulder, and move it outwards and down my bicep until crescent fits my anatomy best. That's where the butt goes.
As far as the rest of the stance:
I am turned in such a way that I am having to turn my head to see the target. Shooting across my chest. Almost perpendicular to the target.
I hold the elbow of my trigger arm (Up/Down) where it fits the best against the buttplate.
I put the elbow of my forward arm against my side and allow gravity to settle the gun into my ribs via my forearm/elbow. The toe area of the buttplate will settle upwards and "lock into place" at this point.
I also tend to lean back a bit, especially if the barrel is of length and heft.
Then all it takes is practice to form the muscle memory.
Ones that say "guns with crescent plates are an awful thing to shoot" just haven't tuned their form, or are overcharging their weapon.