I like disorganizer's idea as well. If a leader is out, unannounced, for 4 days the Pres PM's them. If they do not respond within 3 days they can be removed from office. Filling the office is then done according to established rules.
How about the same with deputies? Or something similar? If a deputy is in a leadership roll then the leader rules apply. That is, if the leader is absent, the deputy assumes control of the department. At that point the deputy would be subject to the 4 day absence, 3 day response rule.
A leader should also be able to fire their deputy. This should be done via poll.
I also think that any leader who is going to be absent for 2 weeks or longer should step down or be removed. Any leader who is going to be absent for 1 week or longer MUST set up a replacement (Judiciary Pro-Tem, Deputy, Acting Governor) or be removed. At an absolute minimum, deputy appointment should be reassigned when a leader is absent.
Yes, governors MAY be able to set a build queue at the beginning of the term and never touch it. A decent build queue CAN last several turns, at least. There ARE ways to get around a missing governor to fix their abandoned mess. So what? This all ignores the fact that governors are elected to a position of trust and are expected to perform their duties. If they won't or can't do this then they do not deserve to have that position.