There is a fundamental problem with 1-L 18 in combination with a plane shift.
The problem isn't with 1-L because 1-L is about Geometrically Oriented Linear Golf. TGM is Hands to Pivot. In this regard, the Shaft always points to the Plane line except when Horizontal to the ground.
The book does help with Pivot Controlled Hands Procedures in some places but for the most part you're on your own.