Sarpedania
And as far as account security and such, WG could host a login server that we connect to and it redirects our accounts to the experimental server. Much like how Everquest Emulator does with their login server.
Another precedent--and a very important one at that--is Myst Online: URU Live. For a while that game existed only on user-run shards accessed via a login server maintained by one employee of Cyan Worlds. That was enough to keep it alive until new commercial interest was found. When that commercial interest eventually failed (because of the publisher having plenty of money but not enough patience), Cyan gradually open-sourced portions of the game (or did they open all of it? I don't remember that detail) and once again ran their own server with the ongoing help of donations. Currently that official shard coexists with user-run shards.