Right hand thumbnail

Trying to learn how to develop my RH thumb rest stroke with minimum movement of the wrist and also to stop some pain in the wrist afer attempting to practice rest strokes with thumb.

Currently trying to keep thumb parallel to strings but found that my last attempt to shape the nail I filed too much off the left side (or side closest to strings), as I also have a "hook" or bend on the sides of thumbnail.

Once the nail is long enough again am thinking to shape it with a reversed ramp than what my i,m and a fingers have.

Am surprised to not find any information specifically for the RH thumbnail. All info and lessons are on i,m & a nails. While some of the content can carry over to the thumbnail it sure would be nice to hear more directly about the various thumbnail shapes and styles of playing, whether or not you use rwst stroke with thumb or not.

Does anyone have any ideas, comments suggestions on RH thumbnail? shapes, methods that have helped develop rest stroke and RH position, etc....?

Thank you,

Brian