It's an interesting point you raise, Xij. Given the precedence of the 'hare' needing to be highlighted outside the grid, you might wonder just how far outside the perimeter of the grid is the admissible range for these letters. What I'm getting at is that only about 3cm to the left of row 8 there already is an 'o' in the phrase 'to arrive by'; only about 1.5cm below column 2 there is already the letter 'e' in the preamble word 'extend'; at about 2cm below column 5 there already is the letter 'n' in the preamble; at about 8.5cm to the right of row 8 there already is the letter 'n' in a jumbo crossword clue. In fact it seems to me that, given the lack of further specification in the preamble, it would be admissible to submit the grid with only one 'extra-grid' added letter, that is the 'd' above column 11. That is, provided that you include enough of the surrounding paper together with the grid so that the letters mentioned above are visible...there is nothing in the preamble to say that this would be wrong...