And looks like you missed this from Pinhead; fairly clever, a secure collar that obstructs access to the saddle clamp bolt. It would make it a pain to adjust the saddle since you have to loosen two things rather than one, but it looks like an effective idea to me!

(Thx for linking, I hadn't heard of Pinhead or Anti-vandale before, good to see Pitlock has competitors; will drive innovation forward and prices down!)