Nice work with the stats! I'm curious, did you use 24 hours instead of 12 for the ship based on the premise that no breaks are needed as it moves?
I'm not sure how I feel about abandoned countries. There's probably
some reasonable amount of time where something could start happening, but it would have to be a while. Maybe a month or two. I like the idea of a person being able to leave for a few weeks and see (hopefully) his country still standing.
In the final game, if I ended up charging a small fee (as discussed in
another thread), then it would probably be more clear cut. If the person is paying, they keep their land. Otherwise, they get a week or two to rejoin and then their stuff goes away.