>While the U.S. Border Patrol primarily operates within 100 miles of the border, it is legally allowed “to operate anywhere in the United States,” the agency added.
The Border Patrol probably is allowed to operate anywhere within the United States, but being in the Border Patrol doesn't (at least statutorily) give them any magic powers; in particular, you don't get "border search authority" by being a part of CBP, but rather by being any law enforcement officer confronting someone who you reasonably believe crossed the border recently.
Just don't book a round trip, don't check a bag, don't do it too often. Also you're gambling that they don't cancel your flight and book you on a new one to the city you don't actually want to go to (that no longer connects via the hidden city). You can get half price tickets sometimes with this trick.
Your solution seemed very smart, and I have no doubt that you are an excellent programmer. However, I think you way over-complicated things by choosing to go the functional route. Here is my go in imperative Python. The base-15 trick is still needed, but the rest of it seems a lot easier to understand for someone reading the code later.
