I guess they have some sort of software that scans for specific types of files. I believe any .gpg, .txt, .asc, .exe file would be more suspicious than a .jpg or .png. I mean, obviously, you can find places to hide your data. Nobody would ever try to manually check 1TB of data. At the same time, automatically scanning using software is faster (good for them) but has security holes (good for the people who want to hide sensitive information)
Let's do this, my seed phrase is
surprise peace famous office settle romance fatigue wood snack episode occur atomI write a letter about a 1. surprise I bought for my wife, but forgot at my 4. office. Then I take a picture 3. famous 2. peace negotiator. I add a small subtle 6. romance text to an old picture of my wife, remebering when we 6. settled down. Just in case, I'll just remember words 7 and 8, and create a similar system for the remaining words. Of course, I restore the original file date on all edited files.
Now that I think about it, just memorizing the words is probably easier
