If BPC hadn't been so set on the cloak-and-dagger shenanigans, they could have sent for a sizeable contingent of the Camerons in the West Bow to come and just generally be present in that part of the Grassmarket.

Good heavens, I'd never thought about that! Though it's very much in-character for BPC to adopt a disguise. He was an adventurer, when all's said and done.