Teamviewer on headless Xubuntu 16.04

I have installed Teamviewer on my headless (no monitor) Ubuntu machine (with desktop included). The problem is that when I connect to it using teamviewer, I get the following screen, and there's nothing I can do. CTRL-ALT key combinations do not work from Teamviewer. Remote VNC is not an option because the machine is located in a firewalled corporate network. I know the desktop is running because if I VNC to it (from within the local network) I can connect to my desktop. Although I don't necessarily want a desktop, just a tty would work for me, but here I don't get a login prompt, the teamviewer screen just stays like the screenshot below. Also, if I connect a monitor, I get a tty prompt just fine. Any ideas on how to get a tty using Teamviewer from this situation? Notes after reading some similar questions: 1. Don't tell me to run VNC instead of Teamviewer. I am in a corporate network I don't control. Tunneling is not an option either. 2. Don't tell me to connect a dummy plug on my video card 3. I'd prefer to avoid the dummy video driver solution. Thanks!