Hello again,
I realized what my problem was...I was trying to make the GUI system read only (i.e. without removing the x server stuff). This leads me to a second question: Is it possible to make a basic Debian system with a GUI truly read only (like squashfs for an i386 architecture)? I assume the risks of running out of the 1GB Raspi memory, if only I knew how to get there.
Many thanks

Hello there,
Thank you for posting this great tutorial!
I tried following your instructions on both Lubuntu 16.04 and on Ubuntu Mate 16.04 but unfortunately my Raspi3 no longer boots after adding the magic word "ro" on the fstab file.
Everything else seems to be working including the tmpfs commands
Any ideas why this would happen? Do these distros differ fundamentally from Rasbian Jessie?

Below are the errors shown on the screen when it hangs:
[34.800508] brcmfmac: brcmf_add_if: ERROR: netdev:wlan0 already exists
[34.800657] brcmfmac: brcmf_add_if: ignore IF event
[35.852809] brcmfmac: brcmf_add_if: ERROR: netdev:wlan0 already exists
[35.853037] brcmfmac: brcmf_add_if: ignore IF event

Thanks much!