Today I was able to convert the /home to an ext4 50 Gb filesystem.
But I could not create logical volumes in that mode, even after a “mount -o remount,rw /” so I had to create the lvm devices in normal mode and do the move mounting the new lv on /mnt.
Let’s see if I can turn /var into a fs. I think there’s no need to do the same to /etc. the size looks to be static.
I repeat, I have no real need to do this, I’m just playing around. 
So far I’m having fun.