Posting here since you locked the thread.
You did it in a pretty messy way, as Ephialtes said.
Personally, I would have added another selection to the default ground texture menu, and then parent envGui_SetVar to delete the ground plane if it was selected.
No annoying slash commands or unneeded client add-ons.
Also, the notification that the server is running the add-on; doing it on a really minor add-on just seems like a shameless e-peen thing to me, especially when you put your name on it.