Does the texture need to be an overlay? If you import the file into Meshlab, you can apply the filter: Transfer texture to vertex color, then transfer the vertex color to face color and export as a new ply mesh with only face color. Then open in 3D Slicer, go to Models and check the “Scalars Visible” box, select RGB from the dropdown and it will load. I also got it to work with an obj as long as the color is “face color.” For some reason, it would not read the color correctly if it was saved in the vertex.
