I would say a better solution would be to delete your wallet app when you cross the boarder. You could easily store your private keys in an encrypted file in the cloud and then retrieve your keys once you have crossed the boarder (it would probably be wise to also transfer your coins to a newly created address at this point).
I also know that if you use a blockchain.info wallet, you can archive your private key so your balance does not appear when you archive an address (although the balance is viewable to someone who knows where to look).
I personally do not think that carrying a private key to an address that contains a lot of bitcoin would be considered to be you carrying a lot of "currency". I also don't think that boarder agents are able to compel you to give up the password and/or unlock your laptop or phone for them to inspect.
Thats what i thought. They can take your personal computers away for investigation then you will have tons of hassle and works to retrieve it back. I remember they said once the computer is in their hands, they just need a warrant to crack it to read data.
I'm still mad, the free land USA is no-longer free in my eyes.
Well I know that the supreme court has previously ruled that boarder agents (meaning the government) is able to search your possessions for illegal contraband in order to protect the country from people bringing in things they should not be bringing in (for example drugs, bombs, ect), but it is not illegal to "bring" bitcoin into the country and anything stored on your computer/phone so I don't see their justification here (although anyone always has the right to
ask to search your belongings, or in this case to search the contents of your phone).
Regarding them being able to crack your phone once they have a warrant - that is correct, assuming you don't have full disk encryption they cannot break or that your phone does not employ encryption that they cannot break. They also need probable cause that you have committed a crime to get a warrant and they would likely not be able to show it based on your refusal to allow them to search your computer/phone.
IMO the simple solution would be to store your private key(s) in an encrypted file that is not labeled as being your keys and you would not have the wallet "loaded" onto any client. You shouldn't be storing 10k worth of bitcoin on your phone anyway as this is not safe and you are almost asking for it to get stolen