I just got the tower expansion myself. It's pretty fun.
But I have to disagree with some of your explanations of the rules.
This is taken from the rio grand website, they have downloadable pdf's of the rules for all their games.
http://riograndegames.com/uploads/Game/Game_58_gameRules.pdf these are the rules for for the tower. In thos rules it says:
"When a player places a follower on a tower, the
tower is completed and may not be further
heightened.
This follower remains on the tower
until the end of the game. The follower cannot
be taken prisoner or taken back by the owning player. Players use this
action to protect their other followers from being taken prisoner"
So, once you stop a tower your guy is stuck there for the rest of the game!
My question about the tower expansion, sadly isn't explained in the rules. But here it goes.
Refering to this picture: (my appologies for the quality- shot on my phone)
if a player places a
second tower piece on the existing one. He should be eligible to capture a meeple two spaces away. This will make the
blue meeple, and the
yellow meeple available to be captured.
My question though, is seeing as there is a gap, and no tile placed inbetween the tower and the
red meeple, is he still eligable to be captured? I personally though no. Blank space is counted as borders in most instances. So I've been playing it as if you wanted to capture
red you would have to first place a tile to connect the ground of the tower to red's tile.
How would you play this scenario? Would you allow the
red meeple to be captured with a second tower piece?