if there was no overlap at the time the first boat entered the two length zone at NO time is a boat authorized to get between you and the mark. You are allowed to round in any method you see fit as long as it is reasonable. Entering wide and existing close is definitely reasonable. If someone sticks his bow in when you do this, he should avoid contact with you and start humping the mark. If there is contact, or you have to avoid in any way, you have been fouled. Obviously, you too should do you part to avoid contact but you should be proudly proclaiming "no room in there! - no overlap!" and then "up up up!" followed by "protest" if he stays on the inside, causes you to avoid him, and/or hits the mark.

If you are behind, occasionally you can sneak one in on the inside of a boat ahead who might be floundering as they attempt a rounding - but you better be sure they can't come up and pinch you at the mark - you are in no-man's land and have no rights.