The ply panel I got didn’t have any holes in it for fixing so I had some fun drilling them in the correct locations. Also for some of the holes the standard VW clips weren’t long enough so I bought a few longer ones from here. For this panel I didn’t care that the clips will be visible except on the LHS where I used hidden clips.
When I test fitted the OSR panel I found that it didn’t sit flush on the LHS edge near the window. There aren’t any standard holes to clip the panel in this location so I made some brackets myself and used rivnuts to fix them.