I've never got into streaming myself but I do think the spectator mode would be appreciated for making player actions clearer. Will you add a 'best guess' of the player's torso position/rotation? I thought that worked well in Fantastic Contraption and Sword Master VR, maybe a floating vest would be appropriate for Eye of the Temple.
I get what you mean about not being able to figure out exactly where the player is standing. It's probably best to keep the safe-zone lenient to prevent irritating edge cases. As you said, there's more to worry about than staying on the current block.
It occurs to me I haven't tried the speed run mode, I should give that a go and try not to trip and hurt myself. :D