Something really useful would be a tweak-fix to fix boats falling into the void, during bad connection or on a slow server, like with terrain gen running.

I would do that by sending the server boat&player position packets with constant y level (maybe using the position of tweak activation). I would name it: boatUnloadedChunkFallFix. If it listens for its hotkey and for sneak, to toggle, it would be pretty nice to use. If you can detect the player being in unloaded chunks that would make it a proper toggleable and nice and clean fix, but I'm not sure wether activating it then would be enough, you could still glitch through floors.

I am aware that this may add limited, probably offensive to use, fly "hacking", I don't think this is an issue.