Ought to be fine, I know it's been done for regular shields. The main thing is it's gotta be safe, and also must fit within the size constraints listed here:
Tower shields must be no wider than your forearm and no taller then the space between your ankle and your collar bone.
Again, though, all weapons and shields must undergo a safety inspection at check-in, and until that point, there's no way of saying whether or not it'll be allowed in game.