[server] Ubuntu LTSP, over internet?

Hi all,

I got a dedicated server running with Proxmox VE.
On that server I got Ubuntu 16.04 with LTSP running.

As you know I can't physically go into the server room and plug in some thin clients to make something like LTSP happen, so I need it over internet.
How can this be achieved?
I got a several options which cam into my mind:
1) VPN (which I don't really like to, since it will only be a test/play setup)
2) Just over the internet (but how?)
3) something like NoVnc(will that actually work?)
4) Replacing LTSP with a Linux Equivalent RDP / RDS ?

Can someone please help me with that?

Thanks in common,
Dennis