Since the navigation information provided in the MD80 is unreliable, it isn't that big a deal that you can't see the display. Navigation in a Douglas product is an "'ish" proposition, followed by vectors. Look out the window and turn at familiar landmarks. If you have not flown that route a million times, then you are probably screwed. Thank God for ASAP and NASA reports.
Have you ever seen a four year old child pour a glass of milk? Douglas RNAV and VNAV are much the same; always hesitant and frequently it ends in something you will have to clean up.