I have a suggestion for the mod: Allowing item stacks to exceed 99.
If you try it in the base game, using save editing, it does actually work - you can even sell in bulk.
If you do something like use the item or interact with it, it will round the stack size down to 99 again though - but this implies that it's a limit Indivi created (for balance purposes?) likely using some function that manually checks the size of any stack you interact with. It should be easy to remove this limit by simply disabling the function or changing the limit of the function to a higher number (I'm not a game dev though, don't quote me on that). The saves should still be compatible with the base game, because it already works when save editors do it (again, don't quote me on that, I'm a mere mortal Python plebe who cowers at the feet of the gods who use real programming languages)