This is going to be interesting . . .

Quote from someone who knows about the Racing Rules:-
"You only get the protection of exoneration if you are in the corridor"
So - not only can you not "shut the door" at mark 3 if you go too low but if your proper course in no longer to sail close to the mark you can be caught port and starboard by a boat coming in late. An extension of the "use it or lose it" principal when it comes to tacking at the windward mark.
Apparently, there is going to be a rapid response team racing call very soon.