Guide:
Southwestern Reaper’s March, in vicinity of POIs like: Crescent River Camp (to the east), Claw’s Strike (public dungeon, to the west) and Jodewood Dolmen (portal, to the south). Southwest of Rawl’kha settlement and its wayshrine.
You want to find the bridge that is just north of a nearby dolmen portal. Collectible is next to a level 39 bandit that is also guarding “The Lusty Argonian Maid Vol.1” lorebook.