I’m not aware of such a blank outline map existing. Your best option might be to cover the game map with several taped-together sheets of clear acetate (the kind used for purposes like overheard projection) and trace the borders with a felt pen to produce a blank outline. You’d then have various options for transfering this outline to the wood surface. A low-tech method would be to cover the wood surface with sheets of carbon paper (if you can still find any, since it’s gone out of style), place your acetate outline over the carbon paper, then trace over the borders with a hard pencil. Alternately, you could scan or digitally photograph your acetate outline and use that as the printing file you mentioned.