Want to add a third monitor - only two ports

Is this possible? I am using my built in graphics ports on my Asus mobo. No room for fancy graphics cards, all my PCI slots are full. I just want a small gui, possibly a tablet, that I can use to display music apps from my PC when I am not facing my monitors. For example sometimes I want notation from a screen.
Is this possible via Blue Tooth or Wifi perhaps? Some other way?

thank you

Z

I have not used any of these but there are quite a few USB 3 to HDMI/DVI adapters available in the $50 to $100 range. Check Amazon or Google it. May work for Cubase which does not need much video bandwidth. Not sure what the USB driver would do to Cubase though.
I have also seen a screen extender adapter that takes a large screen video signal and converts it to two smaller screen video signals. I think it was DVI but may have been Display port to DVI/HDMI.