Citation for the rear gate and its stairs:
A broad stairway, climbed from the Deep up to the Rock and the rear-gate of the Hornburg.
The Two Towers, Chapter VII
EDIT: Oh, OK, you were talking about that thin Dunharrow-like thing. I didn’t even saw it. I understand better why you were talking about a plateau now.
I just found out the map is clearly inspired by Fondstadt’s, btw:
Grimslade/Lumer camp 1 inspiration
Early 14th century village recreation model (from Darwin Reforged discord)
Not sure if its quite the right time period but there’s definitely some stuff in there that could be of use.