This is self-soothing, not a real security plan. It doesn't matter how competent a security agency is, because there's a whole ecosystem of vendors selling into that space; knowledge of how to attack encrypted disks like this is outsourced, and, importantly, those firms have incentives to mop up even random stuff like this, because vendors will be selected in part based on lists of how many different circumvention and privacy tools they can detect.
This isn't stand-up-to-state-actors security. This is keep-state-actors-from-noticing security. They know you're guilty, they'll get it. The XKCD version of password cracking works no matter how secure your hardware.
But while states realistically can crack most anything it doesn't mean they can crack *every*thing. There are simply too many flash drives crossing the border every day.
But there is a big flaw I see: 8gb. You're carting around an 8gb flash drive these days??