For an integer \( n \ge 2 \), if the arithmetic mean of all coefficients in the binomial expansion of \( (x + y)^{2n - 3} \) is \( 16 \), then the distance of point \( P(2n - 1, n^2 - 4n) \) from the line \( x + y = 8 \) is:
\( 3\sqrt{2} \)
\( 5\sqrt{2} \)
\( \sqrt{2} \)
\( 2\sqrt{2} \)