Can you make a stronghold in the squares at the edges of the board? Such a stronghold would have certain corners that were on the board edge itself. You can obviously do this in either of your opponent’s back corners to win, but it’s not clear whether you can do it other places.
Corollary question: If you can build a stronghold in one of those squares, and you do, and your opponent uses Diplomacy to unstronghold you, can they capture your piece by unstrongholding you to one of the corners on the board edge?
Related to that: The rules say you can’t capture by making a stronghold, but don’t address whether you can capture using diplomacy either with the situation above or in other situations (for example, if there are two strongholds that share at least one corner, a Diplomacy card could hypothetically force one of those strongholds onto the shared corner, which would capture the piece being pulled out of stronghold). There is the rule that says: “You may not push with normal movement. Only sword moves and building strongholds can push another pawn,” but this Diplomacy move is not pushing and is not normal movement, so it doesn’t seem to be covered.