Great! Glad you'll be able to present this to your students. The Signed Message solution is pretty clear, too. In fact, Lamport, et al.'s paper was very well laid-out and easy to read / follow.
There was a point where they said to take care of the rigor of the argument for the no solution to the 3 Generals case. They point to reference [3] in their paper which should provide some more formality.