The above is possibly the worst idea possible, as it establishes criminal tax evasion and circumvention of CTR laws, conspiracy to commit at least two federal crimes (two counts for each person involved), and involves trusting an unspecified by presumably large number of third parties to not fvck you over in the long run.
Additionally, the CTR report is triggered at $ 3,000.00 for physical currency transactions. The $ 10,000.00 limit applies only to wires, cheques and other non-currency transactions. This limit is also being toyed with; numerous attempts to drop it even further than $ 2,500.00 have been put forth. So if you're going to do it anyway, make that limit under $3k, not under $5k as suggested.
Ultimately, there is simply no legal way to do what you are talking about doing, and therefore is no truly safe way to do so. If you are bent on doing it anyway try to not take the easiest route imaginable to get your ass busted -- which, after attempting to smuggle in cash in boxes, has got to be the above mentioned process (it's known as "smurfing".) Before involving people that you care about (despite the fact that this means they are probably more trustworthy than a guy in the street) bear in mind that complicity in a federal crime is itself a federal crime, and you can end up getting them into the shit as well if you get in trouble later.
Phaedrus