Thanks for ideas on editing titles. I'll give it a try.
As for defending the Mark. One thing to keep in mind, the forces that would have been sent by Sauron would have been second line. I believe the big blocking force was across from Cair Andros, to hold off the Rohirrim. And the orcish irregulars would have been strung out themselves. You'd need a JRRT to work out the details of movement, forces, etc.
One interesting scenario for the Dunharrow refugees and defenders (whose total would be in the thousands): It's very defensible (PJ got that right geographically in the LoTR movies) but if they were threatened with being overwhelmed they could in desperation try The Paths of the Dead. After all wouldn't the Army of the Dead have been drawn off by Aragorn to South Gondor? After leaving Aragorn it's possible they finally really died and so it was just a long, dark passage to be traversed by Rohan refugees and perhaps 1-2,000 soldiers. And should the Dead still be able, and interested in opposing passage (which seems unlikely from Aragorn's dismissal of them and their relief at ending their [undead?
fate), a large group of Rohan people fleeing for their lives would have been a different order of magnitude from one tipsy lord or even a small group of Rangers.