Re: Alternative Method fo Sankyo
If the people you are working with aren't affecting/controlling uke's center in every technique, or at least trying to, then they aren't really doing the technique. Whether it's sankyo or a kokyunage. Focusing just on the wrist or forearm doesn't seem really acceptable.
Especially with sankyo - they should be trying to make it a structural control, not a point control.
So you have what sounds like a really good approach to me. But it shouldn't be novel to the people you are working with, it should be the basis for what they are doing with this technique.