I have an alternative suggestion for occlusion in Minecraft. Using some sort of beefed up ray casting just to check if a ray collides with a block. If I am not mistaken this should dramatically reduce overdraw and rendered polygons. I mean, when you're in a cave the visible polygon count is probably like in a PS1/N64 era 3D game. I always wondered why would a GPU that can render 10 million polygons a second struggle in Minecraft even on Tiny render distance.
You also shouldn't need much precision due to the block nature of Minecraft, so there should be some computational savings as well.