Well I could just get 2 of the props (models/props_gameplay/sign_gameplay01_witharrow_l.mdl) and the hanging model (which i forgot what it was named) and
Hanging sign: turn 180 degrees, hide the sign
sign_gameplay01_witharrow_l: put it on the hanging thing
It could work, but the hanging model could cause lighting problems. My creativity!
EDIT: Aaaannd the witharrow's model's back would be all nodrawed.