As far as I'm concerned, it's forbidden to alter and modify the files, or otherwise add new ones with the intention of modifying gameplay for just one single player, thus providing them with content exclusive to them. There are very few exceptions like maybe GUI mods (skins) and some retextures (Jilata's riverling retex, Venalan's HD textures, BoneeMods) but adding additional content client-side is not only forbidden but undoable, by the way how PlaneShift works.
So, not only would your idea be against the rules, it would be undoable without a server-wide patch. However, if you're a 3D artist, you can always try to offer your assets to the team. That's the most you could do in regards of your question.