I got a revolutionary idea! Why not make a script or and addon that when changing the weather settings to december, january, february you could be able to change ground textures to snowy textures.
maybe it would require a trigger too with a init line command in the activation field too
the island could have a few scripts having the same kind of system as the bas scripts that would be easy to use and activate.
you can change streetlights and flags and clan tags/flags on vehicles so why not be able to be able to change the ground textures too?
everything would be packed nicely into a single pbo file.