The OP's biggest concern is probably the TSA discovering the cash.
Some TSAers with big-catch syndrome seem to automatically link large amounts of cash to illegal activity, and they will take it upon themselves to report passengers to law enforcement which often takes the same dim view of cash. Their view is tainted by the fact that it is quite easy for law enforcement to seize cash and keep it for their department/agency's use, and quite hard for the victim to get the cash back because the burden of proof is (strangely and disgustingly IMO) on the individual to prove the cash was legit.
See
http://www.flyertalk.com/forum/showthread.php?t=607411
http://www.flyertalk.com/forum/showthread.php?t=446185
Were it me, I would carry a copy of the completed FINCEN form with me to show to TSA (to prove you're following the rules for international travel, even though TSA has no business enforcing those rules). And pack your carry-on and person to minimize the chance of a bag search. And don't "obscure" the cash by hiding it in your sock or the lining of your jacket, or some power-tripping big-catch screener might take that as a sign of suspicious behavior and grounds to refer you to law enforcement for seizure.
Once you get beyond the checkpoint, you shouldn't have any trouble.
I miss living in a free country. It was nice while it lasted.
