I've posted some extra rules and ideas for Dux Bellorum over on Boardgamegeek. These were all tried out during playtesting, but did not make the final cut for a variety of reasons.
They’ve not been
thoroughly tested by me (once the decision was made to cut them, I didn’t
continue testing them, I had enough other rules to work on) … so if you try
any of them out please report back on how you got on via the BGG forum. I’d like to see other
people’s variant rules posted up there too, so if you've been tweaking, get posting!
You can find them here.