Grass in Animal Crossing always has set paths that will deteriorate as a game mechanic every day. It is not possible to do what you are asking with a save editor, and you'd probably be better off finding homebrew that refreshes it for you.
Mind reuploading or that tutorial please? I've been trying to compile the latest with the old wifi.cpp but it never works, and disables me from using wifi settings menu.
Tutorial would be really appreciated.