Discover that your password has ended up in a swap file one day and hasn't been overwritten, and chrome left you logged into Google drive. I wouldn't trust this approach not to fail by accident.
edit: place a big random data file, which looks like encrypted data on your alibi notebook. Refuse to give password and let the government lab try to find the password..
This is certainly safer, though maybe not possible on the return trip (where you're returning from someplace where you only have access to your laptop). If you need to be this careful, maybe it's best to do your work after livebooting into tails or something like that.
> edit: place a big random data file, which looks like encrypted data on your alibi notebook. Refuse to give password and let the government lab try to find the password..
Funny, but unnecessarily risky if you ask me.
head -c 1000000000 /dev/urandom | openssl enc -aes-256-cbc -a > risky.1Giga.file