Convert strokes to texture

It would be extremely useful to me to not rely on brush strokes to transfer work from one mesh to another in some cases. I work a lot on character meshes, with the same topology and the same UVs. I would like to keep my shaders between different shapes of the same mesh. But everything that's painted (painted masks and layers) will transfer in worldspace if they were painted on the mesh. So if I textured a short character mesh and wanted to transfer the smart material to a tall character with the same UVs, I have to redo all the painted masks and layers every time. Which basically means redoing a huge chunk of the work unless I paint the tall guy's textures on the short guy, which is artistically restrictive.

I'd really love an option when selecting a paint layer "Convert strokes to texture" which exports the selected painted layer or mask to a specific resolution and plugs that texture back into the layer using a fill. That way I can keep using the material on other characters without having to flatten everything every time.

This would also be usefull when adding geometry to a character. It happens when I work on the head of a character, then later expand to the body. Adding the body would increase the bounding box so much the transfer wouldn't work anymore. So flattening is the logical solution, but if I then want to tweak the face texture, I'm out of luck.