MOD REQUEST: Hole in the ground (lol)

Hey yall! I'm building an underground cave, which is basically a 2-floor basement, and I'm wracking my brain trying to figure out how to create a deliberate "hole", or an opening in the ground between floor level and the basement. The only thing I've come across is an issue or potential bug that players experienced with platforms, which unintentionally causes missing floor tiles for whatever reason (I've added an example pic), and the solution was to add a roof to the area, which filled the tile back in. I mention this because it seems like it may be possible to be able to accomplish this effect somehow. I'm trying to create a hole effect on the ceiling of the cave-basement so that I can add a waterfall and sunrays (and hopefully light emission). I'm not sure if it can be done, but would somebody please consider making a floor modifier that is a essentially a cutout floor tile? Ideally I would prefer it to look like an actual hole (round, rigid edges, dirt or rock texture), but idk if the game mechanics would allow for that. A simple 1-tile square cutout would be perfect though, and I could just decorate around it.