Started poking at this a bit as an exercise in learning how to write plugins, and it's definitely way over my head still:
The `WantedPoster` class seems pretty simple: An image CRC for the player picture, a player SteamID, and a player name.
...but dealing with images seems complicated. It looks like maybe the server depends on clients to send player images via RPC, so there's probably no way for Monument Addons to synthesize that.
As a compromise, I considered downloading Steam avatars. This is possible via Facepunch's Steamworks library, which appears to be shipped with the server: https://wiki.facepunch.com/steamworks/GetClientAvatarUnity
...but it looks like you have to do the download in the background somehow. Way over my head, but probably possible for an experienced plugin developer. In fact, I saw a paid admin menu plugin on codefling that shows Steam avatars in-game.
Merged post
Took a different approach:
WantedPoster implements ISignage, so with minimal changes to SignArtist and MonumentAddons I am able to load custom image URLs into wanted posters.
In order to control the text displayed on wanted posters, I added support to MonumentAddons' skull name features for the case of a WantedPoster. This almost works - the name gets written to JSON and applied on next profile (re)load - but I can't immediately figure out how to also make the change apply immediately in-game without a profile reload.