I have bee using Encrypted magic Folders for a while now. it gives you the option of encrypting all files in a specific folder. it can also do file name scrambling and even hide all the files in a directory from the OS. It activates through a hot key combination. You work on the files you want and when you exit emf the whole dir is hidden again. probably not the most secure system but it will certainly fool most them if you disable booting from a stiffy/floppy.