Somehow, I missed this thread so I have a late reply.  I am an advocate
of all sorts of modern materials where their use is suitable.  However,
why would anyone even think of repairing a wooden stack board with
plastic?

Wood is one of the easiest materials to patch, with very few special
tools (if any) required.  A sharp chisel is all you need to cut away
the old ragged material in order to glue in a patch which can be glued
in with hide glue or epoxy or any other permanent wood glue.  If you
have a router or a milling machine the job is even easier.

In my opinion, patching a stack board with plastic (other than tiny
spot repairs in which case I would recommend a wood based material
instead) does not come under the definition of professional repair.

Best regards,
Spencer Chase