This mod is cool! however i did notice it does nothing on singleplayer.
I was thinking if you could create a second render distance slider (perhaps through modmenu's config settings), that controlled how far out these "illusion chunks" would render, that could be usefull for high-render distance performance in singleplayer. Since the game would not actually have these chunks active and being saved/loaded/etc constantly, and rather just rendered and nothing else.
Regular render distance setting: same as normal
Mod render distance setting: if larger than regular one, the saved chunks are rendered into the excess area. (essentially the same functionality the mod has right now, but with minor* changes to make it possible to use in singleplayer)