Unfortunately, no solution that relies on this level of coordination will ever work. We cannot even get people to not block the corridor randomly when boarding

Unfortunately, no solution that relies on this level of coordination will ever work. We cannot even get people to not block the corridor randomly when boarding or offboarding, enforcing a routine like this is not going to happen. Sorry for being negative, I like that you came up with something clever. I've seen some similar attempts to make boarding more efficient. I just fly way too frequently and I think the world is not ready for this yet.