Most of the issue can be solved very simply, without any new design. Just board from back to front and/or window to aisle.
Boarding back-to-front doesn't actually reduce the time it takes to board, since the people in row 30 on a narrow-body all can't fit around the overhead at the same time, so the 4 people who can't fit, end up blocking rows 29 and 28, so those people can't sit at all.
Really the best way to board is either window-middle-aisle (also back to front), or to board every 5 rows (30, 25, 20 etc) followed by 29, 24, 19 etc) so multiple rows can board simultaneously. Of course, pesky elites gets in the way.
Still, having a wider aisle allows 2 people to board on oposite sides of the plane (A and F can board at the same time).