Am I missing something here?
Erm, something that I cannot fathom regarding the iPlayer, is: just have a sign-in account to access it. If you've paid your licence fee then all is well and good. If you've not paid, your account is blocked until you top-up your account. Top-up access could be available for a day, a week, a month, or a year - pay online by Paypal or other means. Seems simple to me - no need for WiFi sniffing or whatever.