I was about to use the encryptfs procedure to migrate my existing home folder and discovered that the process needs 2.5x the size of home to complete. I have 258GB in my home, but only 430GB free. Is there a way that I can encrypt home without reinstalling?
Full disclosure here, I'm the co-author and maintainer of the ecryptfs-migrate-home utility.
Note that the 2.5x multiplier is perhaps an aggressive overestimation of the required disk space, but I've published that recommendation as a safety precaution
To answer your question, yes, it is possible, though perhaps slightly risky, and not generally recommended.
You could accomplish this by editing the shell script,
/usr/bin/ecryptfs-migrate-home, and modify the line that looks like this:
rsync -aP "$orig/" "$USER_HOME/" 1>&2
mv -vf "$orig/"* "$orig/".* "$USER_HOME/" 1>&2
This will move files in place, instead of copying them.