A very interesting solution!

If you can do without Windows, I would say formatting a USB with a first partition as an 8 gig DOS partition and a 2nd partition as Linux LUKS may work just a good.

But a few people may know about Linux. So if on OpenBSD, you can create a second OpenBSD encrypted partition. I think that will probably look like garbage to 99.999% of the people you may be hiding from.

Be aware, if dealing with a sophisticated Gov agency, all bets are off.